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45. Jump Game II

Difficulty Topics

Description

You are given a 0-indexed array of integers nums of length n. You are initially positioned at nums[0].

Each element nums[i] represents the maximum length of a forward jump from index i. In other words, if you are at nums[i], you can jump to any nums[i + j] where:

  • 0 <= j <= nums[i] and
  • i + j < n

Return the minimum number of jumps to reach nums[n - 1]. The test cases are generated such that you can reach nums[n - 1].

 

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

Solution

jump-game-ii.py
class Solution:
    def jump(self, nums: List[int]) -> int:
        jumps = currStep = currFarthest = 0

        for i,x in enumerate(nums[:-1]):
            currFarthest = max(currFarthest, i + x)

            if i == currStep:
                jumps += 1
                currStep = currFarthest

        return jumps