The Easiest Problem
阿新 • • 發佈:2018-12-14
http://whu.contest.codeforces.com/group/LqmZzHyOQN/contest/234192/problem/F
題解:
莫名其妙的開瓶子???
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int using namespace std; typedef long long ll; //typedef __int128 lll; const int N=10000; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,q; int a[N]; int b[N]; int c[N]; int main() { #ifdef DEBUG freopen("input.in", "r", stdin); //freopen("output.out", "w", stdout); #endif scanf("%d",&n); int ans=0; for(int i = 1; i <=n; i++){ scanf("%d%d", &a[i],&b[i]); } for(int i = 1; i <=n; i++){ for(int j = 1; j <=n; j++){ if(b[i]==a[j]&&i!=j) c[j]=1; } } for(int i = 1; i <=n; i++){ ans+=c[i]; } cout << n-ans << endl; //cout << "Hello world!" << endl; return 0; }