LeetCode：Jump Game II

最新推荐文章于 2019-01-13 06:57:38 发布

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本文介绍了一个算法问题“跳跃游戏II”，目标是在给定的非负整数数组中，从第一个位置出发到达最后一个位置所需的最少跳跃次数。文章通过示例说明了如何计算最少的跳跃次数，并提供了一种解决方案的实现代码。

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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：

public class Solution {
    public int jump(int[] nums) {
        int minJumpNum = 0;
        int index = 0;
        while (index < nums.length - 1) {
            index = nextIndex(nums, index);
            minJumpNum++;
        }
        return minJumpNum;
    }

    public int nextIndex(int[] nums, int start) {
        int len = nums[start], max = -len;
        if (len >= nums.length - start - 1) {
            return nums.length - 1;
        }
        int nextIndex = start + 1;
        for (int i = 1; i <= len && start + i < nums.length; i++) {
            int nextJumpLen = nums[start + i] - (len - i);
            if (nextJumpLen > max) {
                max = nextJumpLen;
                nextIndex = start + i;
            }
        }
        return nextIndex;
    }
}