45 Jump Game II

Leetcode

Given an array of non-negative integers nums, 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.

You can assume that you can always reach the last index.

Example 1:

Input: nums = [2,3,1,1,4]
Output: 2
Explanation: 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.

Example 2:

Input: nums = [2,3,0,1,4] Output: 2

可以把数组分为很多段 [初始][第 1 步能走到的位置][第 2 步能走到的位置] ... ，每走一步，遍历这一步所有的起始位置，能走到最远的地方是下一段的结尾。

public int jump(int[] nums) {
    int len=nums.length;
    if(len<=1) return 0;
    int begin=0, end=0;
    int step=0;
    while(end<len){
        step++;
        int next=0;
        for(int i=begin;i<=end;++i){
            int t=i+nums[i];
            if(t>next) next=t;
        }
        if(next==len-1) return step;
        begin=end+1;
        end=next;
    }
    return step;
}