From 25a330fcdbc4b2e6958efa51143ce31f476dc60a Mon Sep 17 00:00:00 2001 From: cherrypicker Date: Thu, 21 Dec 2023 15:29:18 +0800 Subject: [PATCH] =?UTF-8?q?Update0704.=E4=BA=8C=E5=88=86=E6=9F=A5=E6=89=BE?= =?UTF-8?q?=20Go=E7=A4=BA=E4=BE=8B=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加注释、计算区间中点mid时使用位运算代替除法运算 --- problems/0704.二分查找.md | 72 ++++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 26 deletions(-) diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md index 590ec1b1..c3783aa3 100644 --- a/problems/0704.二分查找.md +++ b/problems/0704.二分查找.md @@ -251,40 +251,60 @@ class Solution: （版本一）左闭右闭区间 ```go +// 时间复杂度 O(logn) func search(nums []int, target int) int { - high := len(nums)-1 - low := 0 - for low <= high { - mid := low + (high-low)/2 - if nums[mid] == target { - return mid - } else if nums[mid] > target { - high = mid-1 - } else { - low = mid+1 - } - } - return -1 + // 初始化左右边界 + left := 0 + right := len(nums) - 1 + + // 循环逐步缩小区间范围 + for left <= right { + // 求区间中点 + mid := left + (right-left)>>1 + + // 根据 nums[mid] 和 target 的大小关系 + // 调整区间范围 + if nums[mid] == target { + return mid + } else if nums[mid] < target { + left = mid + 1 + } else { + right = mid - 1 + } + } + + // 在输入数组内没有找到值等于 target 的元素 + return -1 } ``` （版本二）左闭右开区间 ```go +// 时间复杂度 O(logn) func search(nums []int, target int) int { - high := len(nums) - low := 0 - for low < high { - mid := low + (high-low)/2 - if nums[mid] == target { - return mid - } else if nums[mid] > target { - high = mid - } else { - low = mid+1 - } - } - return -1 + // 初始化左右边界 + left := 0 + right := len(nums) + + // 循环逐步缩小区间范围 + for left < right { + // 求区间中点 + mid := left + (right-left)>>1 + + // 根据 nums[mid] 和 target 的大小关系 + // 调整区间范围 + if nums[mid] == target { + return mid + } else if nums[mid] < target { + left = mid + 1 + } else { + right = mid + } + } + + // 在输入数组内没有找到值等于 target 的元素 + return -1 } ```