一、题目内容

二、题解

解法1：

思路

二分

代码

public class Solution {
    public int solve (int[] a) {
        // write code here
        if(a[0] != 0){
            return 0;
        }
        int len = a.length;
        if(a[len-1] == len-1){
            return len;
        }
        int left = 0,right = a.length-1;
        while(left<right){
            int p = (left+right)/2;
            if(a[p]!=p){
                right = p;
            }else{
                left = p+1;
            }
        }
        return left;
    }
}