Codeforces Round #501 (Div. 3) A - Points in Segments

http://codeforces.com/contest/1015/problem/A

题意：n个区间，m表示1-m个数

给你n个区间，删除l-r之间的数，最后输出没有被删掉的个数及所有的数

思路：暴力去删，特判0

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
#define ll long long

const int maxn = 1e5+50;
int n, m;
int a[maxn];

int main()
{
        scanf("%d%d", &n, &m);
        int l, r;
        for (int i = 0; i <= m; i ++) {
                a[i] = i;
        }
        for (int i = 0; i < n; i ++) {
                scanf("%d%d", &l, &r);
                for (int i = l; i <= r; i ++) {
                        a[i] = 0;
                }
        }
        int ans = 0;
        for (int i = 1; i <= m; i ++) {
                if (a[i]) ans ++;
        }
        if (ans == 0) printf("0\n");
        else {
        		printf("%d\n", ans);
                for (int i = 0; i <= m; i ++) {
                        if (a[i]) printf("%d ", a[i]);
                }
                printf("\n");        
        }
        
}