牛客多校6-I.Intervals on the Ring

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題意：

思路：

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<bits/stdc++.h>
#include<queue>
#include<string.h>
#include<map>
using namespace std;
#define ll long long
struct node{
  int x,y;
}e[1010],ans[1010];
bool cmp(node a, node b)
{
  return a.x<b.x;
}
int main()
{
  int t;
  cin>>t;
  while(t--)
  {
    memset(e,0,sizeof(e));
    int n,m;
    cin>>n>>m;
    for(int i = 1; i <= m; i++)
    {
      cin>>e[i].x>>e[i].y;
    }
    int cnt = 0,l = 0,r = 0;
    sort(e+1,e+1+m,cmp);
    if(m == 1)
    {
      cout<<1<<endl;
      cout<<e[1].x<<" "<<e[1].y<<endl;
      continue;
    }
    l = e[1].x,r = e[1].y;
    for(int i = 2; i <= m; i++)
    {
      if(i == m)
      {
        if((e[i].y+1)%n != e[1].x)
        {
          ans[++cnt].x = e[1].x,ans[cnt].y = e[m].y;
        }
      }
      if(e[i].x - e[i-1].y == 1)
      {
        r = e[i].y;
      }
      else
      {
        ans[++cnt].x = e[i].x,ans[cnt].y = e[i-1].y;
      }
    }
    if(cnt == 0)
    {
      cout<<1<<endl;
      cout<<1<<" "<<n<<endl;
      continue;
    }
    cout<<cnt<<endl;
    for(int i = 1; i <= cnt; i++)
    cout<<ans[i].x<<" "<<ans[i].y<<endl;
  }
  return 0;
}