Jump Game II

http://blog.youkuaiyun.com/linhuanmars/article/details/21356187

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