35. Search Insert Position.md

35. Search Insert Position

Problem

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.

Here are few examples.

[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

tag:

Solution

Naive的二分搜索循环到l==r时, mid=l=r： 如果target>mid, l++, l指向的是插入的位置 如果target<mid, r--，l指向的是插入的位置 因此 return l;

java

    public int searchInsert(int[] nums, int target) {
        int l = 0, r = nums.length-1;
        while(l<=r) {
            int m = l+(r-l)/2;
            if(target==nums[m]) {
                return m;
            } else if(target<nums[m]){
                r = m-1;
            } else {
                l = m+1;
            }
        }
        return l;
    }

go