#UVa：10963－The Swallowing Ground

檢查每個y1與y2差是否一致即可得解。

C++(0.008)

/*******************************************************/
/* UVa 10963 The Swallowing Ground                     */
/* Author: Maplewing [at] knightzone.studio            */
/* Version: 2012/09/14                                 */
/*******************************************************/
#include<iostream>
#include<cstdio>
using namespace std;

int main(){
  int n, W;
  int y1, y2, dis;
  bool ok;

  while( scanf( "%d", &n ) != EOF ){
    for( int i = 0 ; i < n ; i++ ){
      if( i ) printf( "\n" );
      scanf( "%d", &W );
      ok = true;
      if( W ){
        scanf( "%d%d", &y1, &y2 );
        dis = y1-y2;
        for( int j = 1 ; j < W ; j++ ){
          scanf( "%d%d", &y1, &y2 );
          if( y1-y2 != dis ) ok = false;
        }
      }
      if( ok ) printf( "yes\n" );
      else printf( "no\n" );
    }
  }
  return 0;
}