Jump Game II

Problem Statement

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].

Leetcode Link

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

Code

Python Code

class Solution:
    # @param {integer[]} nums
    # @return {integer}
    def jump(self, nums):
        n, start, end, step = len(nums), 0, 0, 0
        while end < n - 1:
            step += 1
            maxend = end + 1
            for i in range(start, end + 1):
                if i + nums[i] >= n - 1:
                    return step
                maxend = max(maxend, i + nums[i])
            start, end = end + 1, maxend
        return step