Leetcode 55: Jump Game

Question

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.

Solution 1 - Greedy Algorthm

Concept

track the farthest position you can reach as you iterate through the array. If, at any point, the current position exceeds the farthest position you can reach, return false.

Complexity Analysis

1. Time Complexity:
   • O(n)
2. Space Complexity:
   • O(1)

Code

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class Solution:
    def canJump(self, nums: List[int]) -> bool:
        furthest = 0
        for i in range(len(nums)):
            if i > furthest:
                return False
            furthest = max(furthest,i + nums[i])
        
        return True