#include<bits/stdc++.h>
using namespace std;
#include "game.h"
int k1,n1;
vector<vector<int>> G,Grev, DAG;
vector<int> top,used,scc;
int act = 0;
void dfs(int u){
if(used[u]) return;
used[u] = 1;
// cerr<<"START "<<u<<endl;
for(int v : G[u]) dfs(v);
// cerr<<"END "<<u<<endl;
top.push_back(u);
}
void dfs1(int u){
if(used[u]) return;
used[u] = 1;
for(int v : Grev[u]){
dfs1(v);
}
scc[u] = act;
}
void init(int n, int k) {
k1 = k; n1 = n;
G.assign(n,vector<int>());
Grev = G;
// cerr<<"HERE "<<n<<" "<<k<<endl;
for(int i = 0; i<k-1; i++){
G[i].push_back(i+1);
Grev[i+1].push_back(i);
}
}
int add_teleporter(int u, int v) {
G[u].push_back(v);
Grev[v].push_back(u);
used.assign(n1,0);
scc.assign(n1,-1);
top.clear();
// cerr<<"STARTING DFS OF EDGE "<<u<<" "<<v<<endl;
for(int i = 0; i<n1; i++)
dfs(i);
// cerr<<"TOP"<<endl;
for(int i : top) cerr<<i<<" ";
// cerr<<"END TOP"<<endl;
used.assign(n1,0);
act = 0;
for(int i = top.size()-1; i>=0; i--){
if(!used[top[i]]) act++, scc[top[i]] = act, dfs1(top[i]);
}
set<int> hv;
for(int i = 0; i<k1; i++){
hv.insert(scc[i]);
}
// cerr<<"STARTING SCC OF EDGE: "<<u<<" "<<v<<endl;
// for(int i = 0; i<n1; i++){
// cerr<<"SCC: "<<i<<" "<<scc[i]<<endl;
// }
// cerr<<endl;
if(hv.size() <k1) return 1;
for(int i = k1; i<n1; i++){
if(hv.count(scc[i])) return 1;
}
return 0;
}
int read_int() {
int x;
if (scanf("%d", &x) != 1) {
fprintf(stderr , "Error while reading input\n");
exit(1);
}
return x;
}
int main() {
int N = read_int();
int M = read_int();
int K = read_int();
std::vector<int> u(M), v(M);
for (int i = 0; i < M; ++i) {
u[i] = read_int();
v[i] = read_int();
}
init(N, K);
int i;
for (i = 0; i < M; ++i) {
int answer = add_teleporter(u[i], v[i]);
if (answer != 0 && answer != 1) {
i = -1;
break;
} else if (answer == 1) {
break;
}
}
printf("%d\n", i);
return 0;
}
Compilation message
game.cpp: In function 'int add_teleporter(int, int)':
game.cpp:67:15: warning: comparison of integer expressions of different signedness: 'std::set<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
67 | if(hv.size() <k1) return 1;
| ~~~~~~~~~~^~~
/usr/bin/ld: /tmp/cc7nPjAJ.o: in function `main':
stub.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccclZCAM.o:game.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
