LeetCode 045 Jump Game II

题目要求：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.)

 

代码如下：

class Solution {

public:

    int jump(int A[], int n) {

        

        int step = 0;

        int left = 0;

        int right = 0;  //用来记录局部点的最大步长

        

        if(n == 1) return 0;

        

        while(left <= right){

            step++;

            const int old_right = right;

            

            //贪心算法

            //局部最优解

            for(int i = left; i <= old_right; i++){

                //计算每次到达的地方（局部）

                int new_right = i + A[i];

                //如果new_right超过n-1，则表示到了结尾

                if(new_right >= n - 1) return step;

                //保证right是最大

                if(new_right > right) right = new_right;

            }

            

            //左值放在最优解的下一个

            left = old_right + 1;

        }

        

        return 0;

        

    }

};