2022.04.23(LC_1024_视频拼接)

方法：贪心

class Solution {
    public int videoStitching(int[][] clips, int time) {
        //按左端点升序排列(左端点相同时，按右端点降序排列)
        Arrays.sort(clips, (o1, o2) -> {
            if (o1[0] == o2[0]) return o2[1] - o1[1];
            return o1[0] - o2[0];
        });
        if (clips[0][0] != 0) return -1;
        //由排序规则，保证第一个片段一定被选中
        int ans = 1;
        int end = clips[0][1];
        for (int i = 1; i < clips.length; ) {
            if (end >= time) return ans;
            if (clips[i][0] > end) return -1;
            int j = i, maxRight = 0;
            while (j < clips.length && clips[j][0] <= end) {
                maxRight = Math.max(maxRight, clips[j][1]);
                j++;
            }
            if (maxRight >= time) return ans + 1;
            if (maxRight <= end) return -1;
            ans++;
            end = maxRight;
            i = j;
        }
        return end < time ? -1 : ans;
    }
}