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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1001_1100.s1024_video_stitching;

// #Medium #Array #Dynamic_Programming #Greedy #2022_02_26_Time_1_ms_(88.78%)_Space_42.3_MB_(11.00%)

import java.util.Arrays;

/**
 * 1024 - Video Stitching\.
 *
 * Medium
 *
 * 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.
 *
 * Each video clip is described by an array `clips` where clips[i] = [start_i, end_i] indicates that the ith clip started at start_i and ended at end_i.
 *
 * We can cut these clips into segments freely.
 *
 * *   For example, a clip `[0, 7]` can be cut into segments `[0, 1] + [1, 3] + [3, 7]`.
 *
 * Return _the minimum number of clips needed so that we can cut the clips into segments that cover the entire sporting event_ `[0, time]`. If the task is impossible, return `-1`.
 *
 * **Example 1:**
 *
 * **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. 
 *
 * Then, we can reconstruct the sporting event as follows: 
 *
 * We cut [1,9] into segments [1,2] + [2,8] + [8,9]. 
 *
 * Now we have segments [0,2] + [2,8] + [8,10] which cover the sporting event [0, 10].
 *
 * **Example 2:**
 *
 * **Input:** clips = \[\[0,1],[1,2]], time = 5
 *
 * **Output:** -1
 *
 * **Explanation:** We cannot cover [0,5] with only [0,1] and [1,2].
 *
 * **Example 3:**
 *
 * **Input:** clips = \[\[0,1],[6,8],[0,2],[5,6],[0,4],[0,3],[6,7],[1,3],[4,7],[1,4],[2,5],[2,6],[3,4],[4,5],[5,7],[6,9]], time = 9
 *
 * **Output:** 3
 *
 * **Explanation:** We can take clips [0,4], [4,7], and [6,9].
 *
 * **Constraints:**
 *
 * *   `1 <= clips.length <= 100`
 * *   0 <= start_i <= end_i <= 100
 * *   `1 <= time <= 100`
**/
public class Solution {
    public int videoStitching(int[][] clips, int time) {
        Arrays.sort(clips, (a, b) -> a[0] == b[0] ? a[1] - b[1] : a[0] - b[0]);
        int count = 0;
        int covered = 0;
        int i = 0;
        int start = 0;
        while (start < time) {
            while (i < clips.length && clips[i][0] <= start) {
                covered = Math.max(covered, clips[i][1]);
                i++;
            }
            if (start == covered) {
                return -1;
            }
            count++;
            start = covered;
        }
        return count;
    }
}