Video Stitching — LeetCode 1024 Python Solution

The problem

You are given a series of video clips from a sporting event that lasted time seconds. These video clips can be overlapping with each other and have varying lengths.

Example

Input

clips = [[0,2],[4,6],[8,10],[1,9],[1,5],[5,9]], time = 10

Output

3

Explanation

We take the clips [0,2], [8,10], [1,9]; a total of 3 clips.

Python solution

class Solution:
    def videoStitching(self, clips: List[List[int]], time: int) -> int:
        last = [0] * time
        for a, b in clips:
            if a < time:
                last[a] = max(last[a], b)
        ans = mx = pre = 0
        for i, v in enumerate(last):
            mx = max(mx, v)
            if mx <= i:
                return -1
            if pre == i:
                ans += 1
                pre = mx
        return ans

Complexity

Pattern: Greedy

Take the locally best option every time — when you can prove that never costs you later. LeetCode 1024. Video Stitching is filed here because LeetCode tags it Greedy, which is the vocabulary this hub collects.

The greedy guide has the Python template for the pattern and the 346 LeetCode problems that use it.

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