Leetcode 55. Jump Game

You are given an integer array nums. You are initially positioned at the array’s first index, and each element in the array represents your maximum jump length at that position.

Return true if you can reach the last index, or false otherwise.

Example 1:

Input: nums = [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: nums = [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.

The idea is quite simple, we traverse all elements and compare each element with our rest of steps. If the element is greater, then it means, we can have more steps when we reach this element. When steps is down to 0, that means we don’t have any step left, so it’s impossible to reach the end.

class Solution:
    def canJump(self, nums: List[int]) -> bool:
        steps = 0
        index = 0

        while index < len(nums):
            if index == len(nums) - 1:
                return True

            if nums[index] > steps:
                steps = nums[index]
            
            if steps == 0:
                return False
            
            index += 1
            steps -= 1