codeforces #164 div2

http://codeforces.com/problemset/problem/268/Ahttp://codeforces.com/problemset/problem/268/Bhttp://codeforces.com/problemset/problem/268/C// cf #164 div2  A #include<stdio.h>int a[30],b[30];int main(){    //freopen("input.txt","r",stdin);  //  freopen("output.txt","w",stdout);   int  n,i,j,num=0;   scanf("%d",&n);   for(i=0;i<n;i++)    scanf("%d%d",&a[i],&b[i]);     for(i=0;i<n;i++)    for(j=0;j<n;j++)     if(a[i]==b[j])        num++;     printf("%d\n",num);   return 0;}// cf #164 div2 B// 找規律，S=n+ (n-1)+1*(n-2)+ (n-2)+2*(n-3)+ ...+ 3+(n-3)*2+ 2+(n-2)*1+1. #include<stdio.h>int main(){  int i,s,j,n; // freopen("input.txt","r",stdin);  while(scanf("%d",&n)!=EOF&&n>0){    if(n==1){        printf("1\n"); break;    }   if(n==2){    printf("3\n"); break;}  j=1; s=0;  for(i=n-2;i>0;i--){      s+=i*j;      j++;  }  printf("%d\n",s+n*(n+1)/2);}  return 0;}//  cf #164 div2 c // 找出所有滿足條件的點，x+y=min(n,m); 這條直線上的點恰好滿足條件，這個算是水過的吧。
#include<stdio.h>#include<algorithm>#include<iostream>using namespace std;int n, m;int main() {    while (cin >> n >> m) {        int ans = min(n, m) + 1;        cout << ans << endl;        for (int i = 0; i < ans; i++) {            cout << i << " " << ans - i - 1 << endl;        }    }    return 0;}