【LeetCode 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

思路

二分，找第一个 ≥ target 的数字下标。

代码

class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        int n = nums.size();
        int l = 0, r = n-1;
        
        while(l <= r) {
            int mid = l + (r - l) / 2;
            if (nums[mid] >= target) {
                r = mid - 1;
            }else l = mid + 1;
        }
        
        return l;
    }
};