From 5117a288422612c5e4a845d7ecdecff8448334d0 Mon Sep 17 00:00:00 2001 From: Bird Date: Thu, 28 Sep 2023 22:08:12 +0800 Subject: [PATCH 1/2] =?UTF-8?q?feat(0213=20=E6=89=93=E5=AE=B6=E5=8A=AB?= =?UTF-8?q?=E8=88=8D=E2=85=A1):=20=E4=BD=BFGo=E7=89=88=E6=9C=AC=E6=9B=B4?= =?UTF-8?q?=E7=AC=A6=E5=90=88Go=E4=B9=A0=E6=83=AF?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0213.打家劫舍II.md | 44 +++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 19 deletions(-) diff --git a/problems/0213.打家劫舍II.md b/problems/0213.打家劫舍II.md index cd9d596d..385c5867 100644 --- a/problems/0213.打家劫舍II.md +++ b/problems/0213.打家劫舍II.md @@ -225,32 +225,38 @@ class Solution: // 打家劫舍Ⅱ 动态规划 // 时间复杂度O(n) 空间复杂度O(n) func rob(nums []int) int { - if len(nums) == 1 { - return nums[0] + // 如果长度为0或1，那么有没有环的限制都一样 + if len(nums) <= 1 { + return robWithoutCircle(nums) } - if len(nums) == 2 { - return max(nums[0], nums[1]) - } - - result1 := robRange(nums, 0) - result2 := robRange(nums, 1) - return max(result1, result2) + + // 否则，去头或去尾，取最大 + res1 := robWithoutCircle(nums[:len(nums)-1]) + res2 := robWithoutCircle(nums[1:]) + + return max(res1, res2) } -// 偷盗指定的范围 -func robRange(nums []int, start int) int { +// 原始的打家劫舍版 +func robWithoutCircle(nums []int) int { + switch len(nums) { + case 0: return 0 + case 1: return nums[0] + } dp := make([]int, len(nums)) - dp[1] = nums[start] - - for i := 2; i < len(nums); i++ { - dp[i] = max(dp[i - 2] + nums[i - 1 + start], dp[i - 1]) + dp[0]=nums[0] + dp[1] = max(nums[0], nums[1]) + + for i:=2; i b { +func max(a, b int ) int { + if a>b { return a } return b From 546d3b601a2be997855a0d9da2c5af567ebbfaa5 Mon Sep 17 00:00:00 2001 From: Bird Date: Thu, 28 Sep 2023 22:13:00 +0800 Subject: [PATCH 2/2] =?UTF-8?q?feat(1356=20=E6=95=B0=E5=AD=97=E4=BA=8C?= =?UTF-8?q?=E8=BF=9B=E5=88=B61=E6=8E=92=E5=BA=8F):=20=E4=BD=BF=E7=94=A8Go?= =?UTF-8?q?=E5=86=85=E7=BD=AE=E6=8E=92=E5=BA=8F=E5=87=BD=E6=95=B0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...据数字二进制下1的数目排序.md | 41 ++++++++----------- 1 file changed, 17 insertions(+), 24 deletions(-) diff --git a/problems/1356.根据数字二进制下1的数目排序.md b/problems/1356.根据数字二进制下1的数目排序.md index cc7a7007..c2455cf0 100644 --- a/problems/1356.根据数字二进制下1的数目排序.md +++ b/problems/1356.根据数字二进制下1的数目排序.md @@ -171,36 +171,29 @@ class Solution: ```go func sortByBits(arr []int) []int { - var tmp int - for i := 0; i < len(arr); i++ { - for j := i+1; j < len(arr); j++ { - // 冒泡排序的手法，但是排序的规则从比大小变成了比位运算1的个数 - if isCmp(arr[i], arr[j]) { - tmp = arr[i] - arr[i] = arr[j] - arr[j] = tmp - } - } + // 是否arr[i]<=arr[j] + // 先比较1的数量，后比较值本身 + cmp := func(i, j int) bool { + c1, c2 := bitCount(arr[i]), bitCount(arr[j]) + if c1 == c2 { + return arr[i] <= arr[j] + } + return c1 <= c2 } + + // 调用库函数 + // 第一个参数是待排序切片，第二个是第i位是否小于第j位的函数 + sort.Slice(arr, cmp) + return arr } -func isCmp(a, b int) bool { - bitA := bitCount(a) - bitB := bitCount(b) - if bitA == bitB { - return a > b - } else { - return bitA > bitB - } -} - -func bitCount(n int) int { - count := 0 - for n != 0 { - n &= (n-1) // 清除最低位的1 +func bitCount(num int) (count int) { + for num != 0 { + num &= num-1 // 每次运算将最右侧的1变成0 count++ } + return count } ```