From 9a4dab8f898c175559b121f455707eb82452196f Mon Sep 17 00:00:00 2001 From: Camille <59353274+Camille0512@users.noreply.github.com> Date: Fri, 27 Sep 2024 22:49:01 +0800 Subject: [PATCH 1/6] =?UTF-8?q?Update=200099.=E5=B2=9B=E5=B1=BF=E7=9A=84?= =?UTF-8?q?=E6=95=B0=E9=87=8F=E6=B7=B1=E6=90=9C.md=20Add=20Scala=20code=20?= =?UTF-8?q?to=20solve=20counting=20islands=20problem=20on=20LeetCode?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../kamacoder/0099.岛屿的数量深搜.md | 40 +++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/problems/kamacoder/0099.岛屿的数量深搜.md b/problems/kamacoder/0099.岛屿的数量深搜.md index 6ac7ba3b..da1c0739 100644 --- a/problems/kamacoder/0099.岛屿的数量深搜.md +++ b/problems/kamacoder/0099.岛屿的数量深搜.md @@ -412,6 +412,46 @@ const dfs = (graph, visited, x, y) => { ### Swift ### Scala +```scala +import util.control.Breaks._ + +object Solution { + val dir = List((-1,0), (0,-1), (1,0), (0,1)) // 四个方向 + + def dfs(grid: Array[Array[Char]], visited: Array[Array[Boolean]], row: Int, col: Int): Unit = { + (0 until 4).map { x => + val nextR = row + dir(x)(0) + val nextC = col + dir(x)(1) + breakable { + if(nextR < 0 || nextR >= grid.length || nextC < 0 || nextC >= grid(0).length) break + if (!visited(nextR)(nextC) && grid(nextR)(nextC) == '1') { + visited(nextR)(nextC) = true // 经过就记录 + dfs(grid, visited, nextR, nextC) + } + } + } + } + + def numIslands(grid: Array[Array[Char]]): Int = { + val row = grid.length + val col = grid(0).length + var visited = Array.fill(row)(Array.fill(col)(false)) + var counter = 0 + + (0 until row).map{ r => + (0 until col).map{ c => + if (!visited(r)(c) && grid(r)(c) == '1') { + visited(r)(c) = true // 经过就记录 + dfs(grid, visited, r, c) + counter += 1 + } + } + } + + counter + } +} +``` ### C# From 2f58a7b043eeb19eff88c174366db1777a6fff66 Mon Sep 17 00:00:00 2001 From: DraculaJay <113758447+DraculaJay@users.noreply.github.com> Date: Sat, 28 Sep 2024 04:55:41 +0800 Subject: [PATCH 2/6] =?UTF-8?q?0053=20=E6=B7=BB=E5=8A=A0python=E5=8A=A8?= =?UTF-8?q?=E6=80=81=E8=A7=84=E5=88=92=E8=A7=A3=E6=B3=95=E5=92=8C=E5=8A=A8?= =?UTF-8?q?=E6=80=81=E8=A7=84=E5=88=92=E4=BC=98=E5=8C=96=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0053.最大子序和.md | 36 ++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/problems/0053.最大子序和.md b/problems/0053.最大子序和.md index 551c39bf..50757564 100644 --- a/problems/0053.最大子序和.md +++ b/problems/0053.最大子序和.md @@ -229,6 +229,42 @@ class Solution: ``` + +动态规划 + +```python +class Solution: + def maxSubArray(self, nums): + if not nums: + return 0 + dp = [0] * len(nums) # dp[i]表示包括i之前的最大连续子序列和 + dp[0] = nums[0] + result = dp[0] + for i in range(1, len(nums)): + dp[i] = max(dp[i-1]+nums[i], nums[i]) # 状态转移公式 + if dp[i] > result: + result = dp[i] # result 保存dp[i]的最大值 + return result +``` + +动态规划优化 + +```python +class Solution: + def maxSubArray(self, nums: List[int]) -> int: + max_sum = float("-inf") # 初始化结果为负无穷大，方便比较取最大值 + current_sum = 0 # 初始化当前连续和 + + for num in nums: + + # 更新当前连续和 + # 如果原本的连续和加上当前数字之后没有当前数字大，说明原本的连续和是负数，那么就直接从当前数字开始重新计算连续和 + current_sum = max(current_sum+num, num) + max_sum = max(max_sum, current_sum) # 更新结果 + + return max_sum +``` + ### Go 贪心法 ```go From 0ea7587f72abd2c45cc711da696d1c580ddafa06 Mon Sep 17 00:00:00 2001 From: DraculaJay <113758447+DraculaJay@users.noreply.github.com> Date: Sat, 28 Sep 2024 05:04:22 +0800 Subject: [PATCH 3/6] =?UTF-8?q?0055=20=E8=B7=B3=E8=B7=83=E6=B8=B8=E6=88=8F?= =?UTF-8?q?=E6=B7=BB=E5=8A=A0python=20=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0055.跳跃游戏.md | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/problems/0055.跳跃游戏.md b/problems/0055.跳跃游戏.md index 01fd9513..82b433d7 100644 --- a/problems/0055.跳跃游戏.md +++ b/problems/0055.跳跃游戏.md @@ -143,6 +143,23 @@ class Solution: return False ``` +```python +## 基于当前最远可到达位置判断 +class Solution: + def canJump(self, nums: List[int]) -> bool: + far = nums[0] + for i in range(len(nums)): + # 要考虑两个情况 + # 1. i <= far - 表示 当前位置i 可以到达 + # 2. i > far - 表示 当前位置i 无法到达 + if i > far: + return False + far = max(far, nums[i]+i) + # 如果循环正常结束，表示最后一个位置也可以到达，否则会在中途直接退出 + # 关键点在于，要想明白其实列表中的每个位置都是需要验证能否到达的 + return True +``` + ### Go ```go From 754d2d664d848a7f79b7b97347f9fcf27a03749b Mon Sep 17 00:00:00 2001 From: Zhihan Li <54661071+zhihali@users.noreply.github.com> Date: Sun, 29 Sep 2024 23:24:11 +0100 Subject: [PATCH 4/6] =?UTF-8?q?Update=200135.=E5=88=86=E5=8F=91=E7=B3=96?= =?UTF-8?q?=E6=9E=9C.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0135.分发糖果.md | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/problems/0135.分发糖果.md b/problems/0135.分发糖果.md index 6805857e..29eaa06d 100644 --- a/problems/0135.分发糖果.md +++ b/problems/0135.分发糖果.md @@ -177,21 +177,20 @@ class Solution { ```python class Solution: def candy(self, ratings: List[int]) -> int: - candyVec = [1] * len(ratings) + n = len(ratings) + candies = [1] * n - # 从前向后遍历，处理右侧比左侧评分高的情况 - for i in range(1, len(ratings)): + # Forward pass: handle cases where right rating is higher than left + for i in range(1, n): if ratings[i] > ratings[i - 1]: - candyVec[i] = candyVec[i - 1] + 1 + candies[i] = candies[i - 1] + 1 - # 从后向前遍历，处理左侧比右侧评分高的情况 - for i in range(len(ratings) - 2, -1, -1): + # Backward pass: handle cases where left rating is higher than right + for i in range(n - 2, -1, -1): if ratings[i] > ratings[i + 1]: - candyVec[i] = max(candyVec[i], candyVec[i + 1] + 1) + candies[i] = max(candies[i], candies[i + 1] + 1) - # 统计结果 - result = sum(candyVec) - return result + return sum(candies) ``` From d33c76e74aa90b8ba319af04b0c7f731f6bfabca Mon Sep 17 00:00:00 2001 From: 01geek Date: Wed, 9 Oct 2024 16:28:31 +0800 Subject: [PATCH 5/6] =?UTF-8?q?=E7=BA=A0=E6=AD=A3=20problems/1047.?= =?UTF-8?q?=E5=88=A0=E9=99=A4=E5=AD=97=E7=AC=A6=E4=B8=B2=E4=B8=AD=E7=9A=84?= =?UTF-8?q?=E6=89=80=E6=9C=89=E7=9B=B8=E9=82=BB=E9=87=8D=E5=A4=8D=E9=A1=B9?= =?UTF-8?q?.md=20=E4=B8=ADjava=E7=89=88=E6=9C=AC=E7=9B=B8=E5=85=B3?= =?UTF-8?q?=E6=B3=A8=E9=87=8A=EF=BC=9A=E5=B0=86top>0=E7=BA=A0=E6=AD=A3?= =?UTF-8?q?=E4=B8=BAtop>=3D0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/1047.删除字符串中的所有相邻重复项.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/1047.删除字符串中的所有相邻重复项.md b/problems/1047.删除字符串中的所有相邻重复项.md index 7232008a..51ec4e62 100644 --- a/problems/1047.删除字符串中的所有相邻重复项.md +++ b/problems/1047.删除字符串中的所有相邻重复项.md @@ -164,7 +164,7 @@ class Solution { int top = -1; for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); - // 当 top > 0,即栈中有字符时，当前字符如果和栈中字符相等，弹出栈顶字符，同时 top-- + // 当 top >= 0,即栈中有字符时，当前字符如果和栈中字符相等，弹出栈顶字符，同时 top-- if (top >= 0 && res.charAt(top) == c) { res.deleteCharAt(top); top--; From 8f692f8ff4545337e9df4790fa2cdb7f9a07c219 Mon Sep 17 00:00:00 2001 From: 01geek Date: Wed, 9 Oct 2024 17:36:56 +0800 Subject: [PATCH 6/6] =?UTF-8?q?=E7=BA=A0=E6=AD=A3=200150.=E9=80=86?= =?UTF-8?q?=E6=B3=A2=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC?= =?UTF-8?q?.md=20=E7=9A=84c++=E4=BB=A3=E7=A0=81=EF=BC=8C=E5=B0=86=E7=AC=AC?= =?UTF-8?q?21=E8=A1=8C=E4=BB=A3=E7=A0=81=E7=9A=84int=E4=BF=AE=E6=94=B9?= =?UTF-8?q?=E4=B8=BAlong=20long=EF=BC=8C=E5=8E=9F=E5=9B=A0=EF=BC=9A?= =?UTF-8?q?=E6=97=A2=E7=84=B6=E5=89=8D=E9=9D=A2=E8=80=83=E8=99=91=E5=88=B0?= =?UTF-8?q?=E5=8F=AF=E8=83=BD=E6=95=B0=E6=8D=AE=E5=80=BC=E5=A4=A7=E8=80=8C?= =?UTF-8?q?=E5=B0=86int=E6=94=B9=E4=B8=BA=E4=BA=86long=20long=EF=BC=8C?= =?UTF-8?q?=E9=82=A3=E4=B9=88=E6=9C=80=E5=90=8E=E7=9A=84RPN=E8=BF=90?= =?UTF-8?q?=E7=AE=97=E7=BB=93=E6=9E=9C=E4=B9=9F=E5=8F=AF=E8=83=BD=E8=B6=85?= =?UTF-8?q?=E8=BF=87int=E8=83=BD=E8=A1=A8=E7=A4=BA=E7=9A=84=E8=8C=83?= =?UTF-8?q?=E5=9B=B4?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0150.逆波兰表达式求值.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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 48e99c5b..7d4031d7 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 @@ -108,7 +108,7 @@ public: } } - int result = st.top(); + long long result = st.top(); st.pop(); // 把栈里最后一个元素弹出（其实不弹出也没事） return result; }