【leetcode hot 100 35】搜索插入位置

解法一：二分查找法

class Solution {
    public int searchInsert(int[] nums, int target) {
        int n = nums.length;
        int left = 0, right = n - 1, location = n;
        while(left<=right){
            int mid = (left+right)/2;
            if(nums[mid]>=target){
                location = mid;
                right = mid-1;
            }
            else{
                left = mid+1;
            }
        }
        return location;
    }
}

注意：

• location初始化为n，当nums[mid]>=target时更新为mid
• 循环终止条件为left<=right
• 用mid更新时，要记得+1 -1
• 时间复杂度为 O(log n) 的算法 -> 二分查找
• int mid = (left+right)/2 每次都取中间或者中间左边的那个数
• ret=mid 每次都取到最左边的target