From 74b76bfd120446653495d96135e697b5797bae35 Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Thu, 12 May 2022 22:21:29 +0800 Subject: [PATCH 01/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=201002.=E6=9F=A5?= =?UTF-8?q?=E6=89=BE=E5=B8=B8=E7=94=A8=E5=AD=97=E7=AC=A6.md=20Scala?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/1002.查找常用字符.md | 34 ++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/problems/1002.查找常用字符.md b/problems/1002.查找常用字符.md index 36937b0b..075b5ef1 100644 --- a/problems/1002.查找常用字符.md +++ b/problems/1002.查找常用字符.md @@ -418,6 +418,38 @@ char ** commonChars(char ** words, int wordsSize, int* returnSize){ return ret; } ``` - +Scala: +```scala +object Solution { + def commonChars(words: Array[String]): List[String] = { + // 声明返回结果的不可变List集合，因为res要重新赋值，所以声明为var + var res = List[String]() + var hash = new Array[Int](26) // 统计字符出现的最小频率 + // 统计第一个字符串中字符出现的次数 + for (i <- 0 until words(0).length) { + hash(words(0)(i) - 'a') += 1 + } + // 统计其他字符串出现的频率 + for (i <- 1 until words.length) { + // 统计其他字符出现的频率 + var hashOtherStr = new Array[Int](26) + for (j <- 0 until words(i).length) { + hashOtherStr(words(i)(j) - 'a') += 1 + } + // 更新hash，取26个字母最小出现的频率 + for (k <- 0 until 26) { + hash(k) = math.min(hash(k), hashOtherStr(k)) + } + } + // 根据hash的结果转换输出的形式 + for (i <- 0 until 26) { + for (j <- 0 until hash(i)) { + res = res :+ (i + 'a').toChar.toString + } + } + res + } +} +``` -----------------------
From 78c6602ff20c309132007795956f332d66ff7130 Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 10:05:27 +0800 Subject: [PATCH 02/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200349.=E4=B8=A4?= =?UTF-8?q?=E4=B8=AA=E6=95=B0=E7=BB=84=E7=9A=84=E4=BA=A4=E9=9B=86.md=20Sca?= =?UTF-8?q?la=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0349.两个数组的交集.md | 42 ++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/problems/0349.两个数组的交集.md b/problems/0349.两个数组的交集.md index 45f19b6e..49cf4112 100644 --- a/problems/0349.两个数组的交集.md +++ b/problems/0349.两个数组的交集.md @@ -312,7 +312,49 @@ int* intersection1(int* nums1, int nums1Size, int* nums2, int nums2Size, int* re return result; } ``` +Scala: +正常解法: +```scala +object Solution { + def intersection(nums1: Array[Int], nums2: Array[Int]): Array[Int] = { + // 导入mutable + import scala.collection.mutable + // 临时Set，用于记录数组1出现的每个元素 + val tmpSet: mutable.HashSet[Int] = new mutable.HashSet[Int]() + // 结果Set，存储最终结果 + val resSet: mutable.HashSet[Int] = new mutable.HashSet[Int]() + // 遍历nums1，把每个元素添加到tmpSet + nums1.foreach(tmpSet.add(_)) + // 遍历nums2，如果在tmpSet存在就添加到resSet + nums2.foreach(elem => { + if (tmpSet.contains(elem)) { + resSet.add(elem) + } + }) + // 将结果转换为Array返回，return可以省略 + resSet.toArray + } +} +``` +骚操作1: +```scala +object Solution { + def intersection(nums1: Array[Int], nums2: Array[Int]): Array[Int] = { + // 先转为Set，然后取交集，最后转换为Array + (nums1.toSet).intersect(nums2.toSet).toArray + } +} +``` +骚操作2: +```scala +object Solution { + def intersection(nums1: Array[Int], nums2: Array[Int]): Array[Int] = { + // distinct去重，然后取交集 + (nums1.distinct).intersect(nums2.distinct) + } +} +``` ## 相关题目 * 350.两个数组的交集 II From 9f720470e8e2360047052897885261545d0e1ac7 Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 10:29:17 +0800 Subject: [PATCH 03/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200202.=E5=BF=AB?= =?UTF-8?q?=E4=B9=90=E6=95=B0.md=20Scala=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0202.快乐数.md | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/problems/0202.快乐数.md b/problems/0202.快乐数.md index 741a735a..2d0f7d27 100644 --- a/problems/0202.快乐数.md +++ b/problems/0202.快乐数.md @@ -385,5 +385,38 @@ bool isHappy(int n){ return bHappy; } ``` +Scala: +```scala +object Solution { + // 引入mutable + import scala.collection.mutable + def isHappy(n: Int): Boolean = { + // 存放每次计算后的结果 + val set: mutable.HashSet[Int] = new mutable.HashSet[Int]() + var tmp = n // 因为形参是不可变量，所以需要找到一个临时变量 + // 开始进入循环 + while (true) { + val sum = getSum(tmp) // 获取这个数每个值的平方和 + if (sum == 1) return true // 如果最终等于 1，则返回true + // 如果set里面已经有这个值了，说明进入无限循环，可以返回false，否则添加这个值到set + if (set.contains(sum)) return false + else set.add(sum) + tmp = sum + } + // 最终需要返回值，直接返回个false + false + } + + def getSum(n: Int): Int = { + var sum = 0 + var tmp = n + while (tmp != 0) { + sum += (tmp % 10) * (tmp % 10) + tmp = tmp / 10 + } + sum + } +} +``` -----------------------
From be5cc136c56cb194af8ce1d794871ca7af4b1e1d Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 11:00:11 +0800 Subject: [PATCH 04/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200035.=E6=90=9C?= =?UTF-8?q?=E7=B4=A2=E6=8F=92=E5=85=A5=E4=BD=8D=E7=BD=AE.md=20Scala?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0035.搜索插入位置.md | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/problems/0035.搜索插入位置.md b/problems/0035.搜索插入位置.md index 9a770703..3e8cf5c8 100644 --- a/problems/0035.搜索插入位置.md +++ b/problems/0035.搜索插入位置.md @@ -316,7 +316,26 @@ func searchInsert(_ nums: [Int], _ target: Int) -> Int { return right + 1 } ``` - +### Scala +```scala +object Solution { + def searchInsert(nums: Array[Int], target: Int): Int = { + var left = 0 + var right = nums.length - 1 + while (left <= right) { + var mid = left + (right - left) / 2 + if (target == nums(mid)) { + return mid + } else if (target > nums(mid)) { + left = mid + 1 + } else { + right = mid - 1 + } + } + right + 1 + } +} +``` From 95593634b341a951850fae3b5aa739ba7c5d3864 Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 11:01:04 +0800 Subject: [PATCH 05/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200704.=E4=BA=8C?= =?UTF-8?q?=E5=88=86=E6=9F=A5=E6=89=BE.md=20Scala=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0704.二分查找.md | 41 +++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md index 55625130..1e474f9a 100644 --- a/problems/0704.二分查找.md +++ b/problems/0704.二分查找.md @@ -610,7 +610,48 @@ public class Solution{ } } ``` +**Scala:** +（版本一）左闭右闭区间 +```scala +object Solution { + def search(nums: Array[Int], target: Int): Int = { + var left = 0 + var right = nums.length - 1 + while (left <= right) { + var mid = left + ((right - left) / 2) + if (target == nums(mid)) { + return mid + } else if (target < nums(mid)) { + right = mid - 1 + } else { + left = mid + 1 + } + } + -1 + } +} +``` +（版本二）左闭右开区间 +```scala +object Solution { + def search(nums: Array[Int], target: Int): Int = { + var left = 0 + var right = nums.length + while (left < right) { + val mid = left + (right - left) / 2 + if (target == nums(mid)) { + return mid + } else if (target < nums(mid)) { + right = mid + } else { + left = mid + 1 + } + } + -1 + } +} +``` -----------------------
From 9fc232aba413b43fd479ad5b4fd1a186ff90a359 Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 11:01:45 +0800 Subject: [PATCH 06/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200034.=E5=9C=A8?= =?UTF-8?q?=E6=8E=92=E5=BA=8F=E6=95=B0=E7=BB=84=E4=B8=AD=E6=9F=A5=E6=89=BE?= =?UTF-8?q?=E5=85=83=E7=B4=A0=E7=9A=84=E7=AC=AC=E4=B8=80=E4=B8=AA=E5=92=8C?= =?UTF-8?q?=E6=9C=80=E5=90=8E=E4=B8=80=E4=B8=AA=E4=BD=8D=E7=BD=AE.md=20Sca?= =?UTF-8?q?la=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...元素的第一个和最后一个位置.md | 45 +++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/problems/0034.在排序数组中查找元素的第一个和最后一个位置.md b/problems/0034.在排序数组中查找元素的第一个和最后一个位置.md index dfd90b82..260462c2 100644 --- a/problems/0034.在排序数组中查找元素的第一个和最后一个位置.md +++ b/problems/0034.在排序数组中查找元素的第一个和最后一个位置.md @@ -480,7 +480,52 @@ var searchRange = function(nums, target) { return [-1, -1]; }; ``` +### Scala +```scala +object Solution { + def searchRange(nums: Array[Int], target: Int): Array[Int] = { + var left = getLeftBorder(nums, target) + var right = getRightBorder(nums, target) + if (left == -2 || right == -2) return Array(-1, -1) + if (right - left > 1) return Array(left + 1, right - 1) + Array(-1, -1) + } + // 寻找左边界 + def getLeftBorder(nums: Array[Int], target: Int): Int = { + var leftBorder = -2 + var left = 0 + var right = nums.length - 1 + while (left <= right) { + var mid = left + (right - left) / 2 + if (nums(mid) >= target) { + right = mid - 1 + leftBorder = right + } else { + left = mid + 1 + } + } + leftBorder + } + + // 寻找右边界 + def getRightBorder(nums: Array[Int], target: Int): Int = { + var rightBorder = -2 + var left = 0 + var right = nums.length - 1 + while (left <= right) { + var mid = left + (right - left) / 2 + if (nums(mid) <= target) { + left = mid + 1 + rightBorder = left + } else { + right = mid - 1 + } + } + rightBorder + } +} +``` -----------------------
From f131f27744693b91f40df4ea0fb7c1578bd6647b Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 13 May 2022 11:02:19 +0800 Subject: [PATCH 07/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200027.=E7=A7=BB?= =?UTF-8?q?=E9=99=A4=E5=85=83=E7=B4=A0.md=20Scala=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0027.移除元素.md | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md index 590cf0b9..5ff327fb 100644 --- a/problems/0027.移除元素.md +++ b/problems/0027.移除元素.md @@ -328,6 +328,20 @@ int removeElement(int* nums, int numsSize, int val){ return slow; } ``` - +Scala: +```scala +object Solution { + def removeElement(nums: Array[Int], `val`: Int): Int = { + var slow = 0 + for (fast <- 0 until nums.length) { + if (`val` != nums(fast)) { + nums(slow) = nums(fast) + slow += 1 + } + } + slow + } +} +``` -----------------------
From 495998e509527b53a8b84cc0527dfcff4fc1e1af Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 13 May 2022 12:07:52 +0800 Subject: [PATCH 08/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880188.=E4=B9=B0?= =?UTF-8?q?=E5=8D=96=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6?= =?UTF-8?q?=E6=9C=BAIV.md=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0typescript?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0188.买卖股票的最佳时机IV.md | 22 +++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/problems/0188.买卖股票的最佳时机IV.md b/problems/0188.买卖股票的最佳时机IV.md index 61c558a1..27eb38c3 100644 --- a/problems/0188.买卖股票的最佳时机IV.md +++ b/problems/0188.买卖股票的最佳时机IV.md @@ -409,5 +409,27 @@ var maxProfit = function(k, prices) { }; ``` +TypeScript： + +```typescript +function maxProfit(k: number, prices: number[]): number { + const length: number = prices.length; + if (length === 0) return 0; + const dp: number[][] = new Array(length).fill(0) + .map(_ => new Array(k * 2 + 1).fill(0)); + for (let i = 1; i <= k; i++) { + dp[0][i * 2 - 1] = -prices[0]; + } + for (let i = 1; i < length; i++) { + for (let j = 1; j < 2 * k + 1; j++) { + dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - 1] + Math.pow(-1, j) * prices[i]); + } + } + return dp[length - 1][2 * k]; +}; +``` + + + -----------------------
From 127986e03a0b4acdedf80a6b38d3ded7d61514f3 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 13 May 2022 16:19:59 +0800 Subject: [PATCH 09/11] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880309.=E6=9C=80?= =?UTF-8?q?=E4=BD=B3=E4=B9=B0=E5=8D=96=E8=82=A1=E7=A5=A8=E6=97=B6=E6=9C=BA?= =?UTF-8?q?=E5=90=AB=E5=86=B7=E5=86=BB=E6=9C=9F.md=EF=BC=89=EF=BC=9A?= =?UTF-8?q?=E5=A2=9E=E5=8A=A0typescript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...09.最佳买卖股票时机含冷冻期.md | 60 +++++++++++++++++++ 1 file changed, 60 insertions(+) diff --git a/problems/0309.最佳买卖股票时机含冷冻期.md b/problems/0309.最佳买卖股票时机含冷冻期.md index f3e7541b..f037fe85 100644 --- a/problems/0309.最佳买卖股票时机含冷冻期.md +++ b/problems/0309.最佳买卖股票时机含冷冻期.md @@ -325,6 +325,66 @@ const maxProfit = (prices) => { }; ``` +TypeScript： + +> 版本一，与本文思路一致 + +```typescript +function maxProfit(prices: number[]): number { + /** + dp[i][0]: 持股状态； + dp[i][1]: 无股状态，当天为非冷冻期； + dp[i][2]: 无股状态，当天卖出； + dp[i][3]: 无股状态，当天为冷冻期； + */ + const length: number = prices.length; + const dp: number[][] = new Array(length).fill(0).map(_ => []); + dp[0][0] = -prices[0]; + dp[0][1] = dp[0][2] = dp[0][3] = 0; + for (let i = 1; i < length; i++) { + dp[i][0] = Math.max( + dp[i - 1][0], + Math.max(dp[i - 1][1], dp[i - 1][3]) - prices[i] + ); + dp[i][1] = Math.max(dp[i - 1][1], dp[i - 1][3]); + dp[i][2] = dp[i - 1][0] + prices[i]; + dp[i][3] = dp[i - 1][2]; + } + const lastEl: number[] = dp[length - 1]; + return Math.max(lastEl[1], lastEl[2], lastEl[3]); +}; +``` + +> 版本二，状态定义略有不同，可以帮助理解 + +```typescript +function maxProfit(prices: number[]): number { + /** + dp[i][0]: 持股状态，当天买入； + dp[i][1]: 持股状态，当天未买入； + dp[i][2]: 无股状态，当天卖出； + dp[i][3]: 无股状态，当天未卖出； + + 买入有冷冻期限制，其实就是状态[0]只能由前一天的状态[3]得到； + 如果卖出有冷冻期限制，其实就是[2]由[1]得到。 + */ + const length: number = prices.length; + const dp: number[][] = new Array(length).fill(0).map(_ => []); + dp[0][0] = -prices[0]; + dp[0][1] = -Infinity; + dp[0][2] = dp[0][3] = 0; + for (let i = 1; i < length; i++) { + dp[i][0] = dp[i - 1][3] - prices[i]; + dp[i][1] = Math.max(dp[i - 1][1], dp[i - 1][0]); + dp[i][2] = Math.max(dp[i - 1][0], dp[i - 1][1]) + prices[i]; + dp[i][3] = Math.max(dp[i - 1][3], dp[i - 1][2]); + } + return Math.max(dp[length - 1][2], dp[length - 1][3]); +}; +``` + + + -----------------------
From 6c0d4365c6ed1e9a47c5f31e14d59912648f4afa Mon Sep 17 00:00:00 2001 From: lizhendong128 Date: Fri, 13 May 2022 17:26:03 +0800 Subject: [PATCH 10/11] =?UTF-8?q?=E4=BF=AE=E6=94=B90059=E8=9E=BA=E6=97=8B?= =?UTF-8?q?=E7=9F=A9=E9=98=B5II=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 精简Java代码中不必要的变量，调整结构，减少代码量，使代码更加易读 --- problems/0059.螺旋矩阵II.md | 44 +++++++++------------------------ 1 file changed, 12 insertions(+), 32 deletions(-) diff --git a/problems/0059.螺旋矩阵II.md b/problems/0059.螺旋矩阵II.md index 93735895..7afc1575 100644 --- a/problems/0059.螺旋矩阵II.md +++ b/problems/0059.螺旋矩阵II.md @@ -130,57 +130,37 @@ Java： ```Java class Solution { public int[][] generateMatrix(int n) { + int loop = 0; // 控制循环次数 int[][] res = new int[n][n]; + int start = 0; // 每次循环的开始点(start, start) + int count = 1; // 定义填充数字 + int i, j; - // 循环次数 - int loop = n / 2; - - // 定义每次循环起始位置 - int startX = 0; - int startY = 0; - - // 定义偏移量 - int offset = 1; - - // 定义填充数字 - int count = 1; - - // 定义中间位置 - int mid = n / 2; - while (loop > 0) { - int i = startX; - int j = startY; - + while (loop++ < n / 2) { // 判断边界后，loop从1开始 // 模拟上侧从左到右 - for (; j startY; j--) { + for (; j >= loop; j--) { res[i][j] = count++; } // 模拟左侧从下到上 - for (; i > startX; i--) { + for (; i >= loop; i--) { res[i][j] = count++; } - - loop--; - - startX += 1; - startY += 1; - - offset += 2; + start++; } if (n % 2 == 1) { - res[mid][mid] = count; + res[start][start] = count; } return res; From 0b88af0824b696be6d2f107adde3758f1df1c3f8 Mon Sep 17 00:00:00 2001 From: lizhendong128 Date: Thu, 19 May 2022 11:08:59 +0800 Subject: [PATCH 11/11] =?UTF-8?q?=E4=BF=AE=E6=94=B90150=E9=80=86=E6=B3=A2?= =?UTF-8?q?=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC=20Java?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 将for循环改为for each，使代码更加简洁。因为循环除了对token进行遍历，i并没有其他用途。 --- problems/0150.逆波兰表达式求值.md | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/problems/0150.逆波兰表达式求值.md b/problems/0150.逆波兰表达式求值.md index fd3d69aa..6ce7e2f9 100644 --- a/problems/0150.逆波兰表达式求值.md +++ b/problems/0150.逆波兰表达式求值.md @@ -136,19 +136,19 @@ java: class Solution { public int evalRPN(String[] tokens) { Deque stack = new LinkedList(); - for (int i = 0; i < tokens.length; ++i) { - if ("+".equals(tokens[i])) { // leetcode 内置jdk的问题，不能使用==判断字符串是否相等 + for (String s : tokens) { + if ("+".equals(s)) { // leetcode 内置jdk的问题，不能使用==判断字符串是否相等 stack.push(stack.pop() + stack.pop()); // 注意 - 和/ 需要特殊处理 - } else if ("-".equals(tokens[i])) { + } else if ("-".equals(s)) { stack.push(-stack.pop() + stack.pop()); - } else if ("*".equals(tokens[i])) { + } else if ("*".equals(s)) { stack.push(stack.pop() * stack.pop()); - } else if ("/".equals(tokens[i])) { + } else if ("/".equals(s)) { int temp1 = stack.pop(); int temp2 = stack.pop(); stack.push(temp2 / temp1); } else { - stack.push(Integer.valueOf(tokens[i])); + stack.push(Integer.valueOf(s)); } } return stack.pop();