45. Jump Game II

Problem Link

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
• It's guaranteed that you can reach nums[n - 1].

Solution

---

Python3

class Solution:
    def jump(self, nums: List[int]) -> int:
        N = len(nums)
        count = maxSoFar = end = i = 0
 
        while i < N and end < N - 1:
            count += 1
 
            while i < N and i <= end:
                maxSoFar = max(maxSoFar, i + nums[i])
                i += 1
            
            end = maxSoFar
        
        return count