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#include <vector> #include <list> #include <map> #include <set> #include <deque> #include <queue> #include <stack> #include <bitset> #include <algorithm> #include <functional> #include <numeric> #include <utility> #include <sstream> #include <iostream> #include <iomanip> #include <cstdio> #include <cmath> #include <cstdlib> #include <ctime> #include <math.h> #include <limits.h> #include <hash_map> using namespace std; // Datatypes typedef vector<int> vi; typedef vector<string> vs; typedef vector<vi> vvi; typedef pair<int,int> ii; typedef long long ll; typedef long double ld; // Define #define sz(a) int((a).size()) #define pb push_back #define all(c) (c).begin(),(c).end() #define present(c,x) ((c).find(x) != (c).end()) #define cpresent(c,x) (find(all(c),x) != (c).end()) #define FOR(_i,_n) for(int (_i) = 0; (_i) < (_n); (_i)++) #define mp make_pair // Constants const double eps = 1e-8; const double PI = 3.1415926535897932384626433832795; #define INPUT_FILE "xo.in" #define OUTPUT_FILE "xo.out" #define WHITE 0 #define GREY 1 #define BLACK 2 vector< vector<int> > g; vector< int > color; vector< int > order; int main(void) { #ifdef ALEX freopen("input.in", "r", stdin); freopen("output.out", "w", stdout); #else //freopen(INPUT_FILE, "r", stdin); //freopen(OUTPUT_FILE, "w", stdout); #endif int N, M; cin >> N >> M; g.resize(N); color.resize(N); for(int i = 0; i < M; i++) { int u,v; cin >> u >> v; g[u-1].pb(v-1); } for(int i = 0; i < N; i++) { int u; cin >> u; order.pb(u-1); } reverse(order.begin(), order.end()); for(int i = 0; i < N; i++) { int u = order[i]; for(int i = 0; i < sz(g[u]); i++) { if(color[g[u][i]] != BLACK ) { cout << "NO"; exit(0); } } color[u] = BLACK; } cout << "YES"; return 0; }
page revision: 0, last edited: 14 Sep 2007 06:37