55. Jump Game

描述

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.

Example 1:

Input: [2,3,1,1,4]
Output: true
Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.

Example 2:

Input: [3,2,1,0,4]
Output: false
Explanation: You will always arrive at index 3 no matter what. Its maximum
             jump length is 0, which makes it impossible to reach the last index.

解法

动态规划

class Solution:
    def canJump(self, nums: List[int]) -> bool:
        if not nums:
            return True

        dp = [False] * len(nums)
        dp[0] = True

        for i in range(1, len(nums)):
            for j in range(0, i):
                if dp[j] and j + nums[j] >= i:
                    dp[i] = True
                    break
            # else:
            #     dp[i] = False
            # default is False, so unnecessary to change it

        return dp[-1]

$O(N^2)$ 的复杂度超时了。

贪心

引用