35. Search Insert Position

题目描述

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Example 1:

Input: [1,3,5,6], 5
Output: 2

Example 2:

Input: [1,3,5,6], 2
Output: 1

Example 3:

Input: [1,3,5,6], 7
Output: 4

Example 4:

Input: [1,3,5,6], 0
Output: 0

JS 解法

使用二分查找的算法，时间复杂度为 O(logN):

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
let searchInsert = function(nums, target) {
    
    if (target < nums[0]) return 0;
    else if (nums[nums.length-1] < target) return nums.length;
    else {
        let left = 0;
        let right = nums.length;
        while(left <= right){
            let mid = Math.floor((left + right) / 2);
            if (target === nums[mid] || (target < nums[mid] && nums[mid-1] < target)) {
               return mid
            }else if (target < nums[mid]) {
                right = mid - 1;
            }else {
                left = mid + 1;
            }
        }
    }

};