[Leetcode] Jump Game / Jump Game II

跳跃游戏算法解析

最新推荐文章于 2025-05-22 14:52:23 发布

最新推荐文章于 2025-05-22 14:52:23 发布 · 107 阅读

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本文介绍了一种名为Jump Game的问题解决方案，包括两个子问题：一是判断能否到达数组末尾，二是求解达到末尾所需的最少跳跃次数。通过示例说明了算法的工作原理，并提供了C++实现代码。

Jump GameMar 25 '126923 / 16241

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.

Determine if you are able to reach the last index.

For example:
A = [2,3,1,1,4], return true.

A = [3,2,1,0,4], return false.

Jump Game IIMar 17 '126747 / 18561

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.)

class Solution {
public:
    bool canJump(int A[], int n) {
        int last = 0, t;
        for (int i = 0; i < n; i++) {
            if (i <= last) {
                t = i + A[i];
                if (last < t) last = t;
                if (last >= n-1) return true;
            } else return false;
        }
        return last >= n-1;
    }
};


class Solution {
public:
    int jump(int A[], int n) {
        int last = 0, step = 0, cur = 0, t;
        while (last < n-1) {
            int nextlast = last;
            for (int i = cur; i <= last; i++) {
                t = i + A[i];
                if (t > nextlast) nextlast = t;
            }
            step++;
            cur = last + 1;
            last = nextlast;
        }
        return step;
    }
};