35. Search Insert Position

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

 

含义：给定一个target，和有序序列，如果target在序列中，则返回其索引，否则给出当插入target且不改变序列性质时插入的位置（索引）。

思路：二分查找，找到就很简单直接返回，没找到，这个时候判断nums[mid]和target的关系。

    public int searchInsert(int[] nums, int target) {
        int low = 0, high = nums.length-1;
        while(low<=high){
            int mid = (low+high)/2;
            if(nums[mid] == target) return mid;
            else if(nums[mid] > target) high = mid-1;
            else low = mid+1;
        }
        return low;    
    }