牛客网：几步可以从头跳到尾

import java.util.*;


public class Solution {
    
    public int Jump (int n, int[] A) {
        // write code here
        int ans = 0;
        int pre = 0;
        int cur = 0;
        for (int i = 0; i < n - 1; i++){
            cur = Math.max(cur, i + A[i]);
            if (i == pre){
                pre = cur;
                ans++;
            }
        }
        return ans;
    }
}