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k-induced-path-naive.cpp
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k-induced-path-naive.cpp
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/*
Autore: Gaspare Ferraro
Conta i k-path indotti in un grafo non orientato
con una dfs
*/
#include <bits/stdc++.h>
using namespace std;
int N, M, k;
set<int> *G;
int nextInt() {
int tmp;
scanf("%d", &tmp);
return tmp;
}
bool *in;
vector<int> path;
long long cont = 0;
void dfs(int a) {
bool induced = true;
for (int i = 0; i < (int)path.size() - 1 && induced; i++) {
if (G[path[i]].find(a) != G[path[i]].end()) induced = false;
}
if (!induced) return;
path.push_back(a);
in[a] = true;
if (path.size() == (size_t)k) {
cont++;
// for(int i : path)
// printf("%d ", i);
// printf("\n");
} else {
for (int b : G[a]) {
if (in[b]) continue;
dfs(b);
}
}
in[a] = false;
path.pop_back();
}
int main(int argc, char **argv) {
if (argc < 2) {
printf("Usage: ./%s k\n", argv[0]);
}
k = atol(argv[1]);
N = nextInt();
M = nextInt();
G = new set<int>[N];
in = new bool[N];
for (int i = 0; i < M; i++) {
int a = nextInt();
int b = nextInt();
G[a].insert(b);
G[b].insert(a);
}
for (int i = 0; i < N; i++) dfs(i);
printf("%llu\n", cont);
return 0;
}