Leetcode:Jump Game II

Given an array of non-negative integers, you are initially positioned at the first index of the array.

Each element in the array represents your maximum jump length at that position.

Your goal is to reach the last index in the minimum number of jumps.

For example:
Given array A = [2,3,1,1,4]

The minimum number of jumps to reach the last index is 2. (Jump 1 step from index 0 to 1, then 3 steps to the last index.)

分析：貪心算法。關鍵在於維護當前step生成的window最右端和step+1生成的window最右端。若是當前window最右端大於等於n-1，那麼返回step。代碼以下：

class Solution {
public:
    int jump(int A[], int n) {
        int step = 0;
        if(n == 1) return step;
        int right = 0, old_right = 0;
        
        for(int i = 0; i < n; i++){
            if(i > old_right){
                step++;
                old_right = right;
            }
            right = max(right, i+A[i]);
        }
        
        return step;
    }
};