[leetcode] 45. Jump Game II

题目

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

Constraints:

• 1 <= nums.length <= 104
• 0 <= nums[i] <= 1000

思路

贪婪算法，题意是要求算法最小步数，那么就算出每一步能够跨出的最长路径，从而得出结果。

代码

python版本：

class Solution:
    def jump(self, nums: List[int]) -> int:
        l, r = 0, 0
        cnt = 0
        while r < len(nums)-1:
            l, r = r, max(i+nums[i] for i in range(l, r+1))
            cnt += 1
        return cnt