用来验证的暴力解

 public static class Program{
        public int start;
        public int end;
        public Program(int start, int end) {
            this.start = start;
            this.end = end;
        }
    }
    /*
    暴力解
     */
    public static int bestArrange(Program[] programs) {
        if (programs == null || programs.length == 0) {
            return 0;
        }
        return process(programs, 0, 0);
    }
    /*
        目前来到timeLine的时间点，已经安排了done多的会议，剩下的会议programs可以自由安排
     */
    private static int process(Program[] programs, int done, int timeLine) {
        if (programs.length == 0) {
            return done;
        }
        // 还有会议可以选择
        int max = done;
        // 当前安排的会议是什么会，每个都枚举
        for (int i = 0; i < programs.length; i++) {
            if (programs[i].start >= timeLine) {
                Program[] next = copyButExcept(programs, i);
                max = Math.max(max, process(next, done + 1, programs[i].end));
            }
        }
        return max;
    }
    private static Program[] copyButExcept(Program[] programs, int i) {
        Program[] ans = new Program[programs.length - 1];
        int index = 0;
        for (int k = 0; k < programs.length; k++) {
            if (k != i) {
                ans[index++] = programs[k];
            }
        }
        return ans;
    }

贪心

     /*
       法二：按每场的结束时间
     */
    public static int bestArrange2(Program[] programs) {
        Arrays.sort(programs, (o1, o2) -> o1.end - o2.end);
        int timeLine = 0;
        int result = 0;
        for (int i = 0; i < programs.length; i++) {
            if (programs[i].start >= timeLine) {
                result++;
                timeLine = programs[i].end;
            }
        }
        return result;
    }