[原题链接](https://leetcode-cn.com/problems/binary-search/solution/qian-duan-shi-tang-ti-jie-chao-hao-li-ji-36k8/) ## 二分查找 理解二分算法可以参考:[二分查找详解](https://leetcode-cn.com/problems/binary-search/solution/er-fen-cha-zhao-xiang-jie-by-labuladong/) ```js // 左闭右闭区间 const search = function(nums, target) { let start = 0 let end = nums.length - 1 while (start <= end) { const mid = start + ((end - start) >> 1) if (nums[mid] === target) return mid if (nums[mid] < target) { start = mid + 1 } else { end = mid - 1 } } return -1 } ``` ```js // 左闭右开区间 const search = function(nums, target) { let start = 0 let end = nums.length while (start < end) { const mid = start + ((end - start) >> 1) if (nums[mid] === target) return mid if (nums[mid] < target) { start = mid + 1 } else { end = mid } } return -1 } ``` - 时间复杂度:O(logn) - 空间复杂度:O(1)
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