HihoCoder

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;const int maxn = 1e5 + 10;const int maxm = 4 * 1e5 + 10;int tot;int head[maxn];int vis[maxn];struct Edge {    int to, next;}edge[maxm<<1];void init(int n) {    tot = 0;    for (int i = 0; i <= n; i++) head[i] = -1, vis[i] = 0;}void addedge(int u, int v) {    tot++;    edge[tot].to = v;    edge[tot].next = head[u];    head[u] = tot;}bool dfs(int u) {    for (int i = head[u]; i != -1; i = edge[i].next) {        int v = edge[i].to;        if (vis[v]) {            if (vis[v] == -vis[u]) continue;            else return false;        }        else {            vis[v] = -vis[u];            if (!dfs(v)) return false;        }    }    return true;}int main() {    int T; scanf("%d", &T);    for (int kase = 1; kase <= T; kase++) {        int n, m; scanf("%d %d", &n, &m);        init(n);        for (int i = 1; i <= m; i++) {            int u, v; scanf("%d %d", &u, &v);            addedge(u, v); addedge(v, u);        }        bool ok = true;        for (int i = 1; i <= n; i++) {            if (!vis[i]) {                vis[i] = 1;                if (!dfs(i)) { ok = false; break; }            }        }        if (ok) printf("Correct\n");        else printf("Wrong\n");    }}