Leetcode45 Jump Game II

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.)

Solution

将数组划分成一个个区间，每一个区间都是当前能够到达的最远位置内。

public class Solution {
public int jump(int[] nums) {
int step = 0, farthest = 0, next = 0;
for(int i=0;i<nums.length;i++){
if(next<i) return -1;//到达不了末尾
if(i>farthest){
step++;
farthest = next;
}
next = Math.max(next,i+nums[i]);
}
return step;
}
}