【BZOJ1116】[POI2008]CLO【BFS】

/* Pigonometry */
#include <cstdio>
#include <algorithm>

using namespace std;

const int maxn = 100005, maxm = 200005, maxq = maxn;

int n, m, head[maxn], cnt, q[maxq];
bool vis[maxn];

struct _edge {
int v, next;
} g[maxm << 1];

inline int iread() {
int f = 1, x = 0; char ch = getchar();
for(; ch < '0' || ch > '9'; ch = getchar()) f = ch == '-' ? -1 : 1;
for(; ch >= '0' && ch <= '9'; ch = getchar()) x = x * 10 + ch - '0';
return f * x;
}

inline void add(int u, int v) {
g[cnt] = (_edge){v, head[u]};
head[u] = cnt++;
}

inline bool bfs(int x) {
int h = 0, t = 0, node = 0, edge = 0;
vis[q[t++] = x] = 1;
while(h != t) {
int u = q[h++];
node++;
for(int i = head[u]; ~i; i = g[i].next) {
edge++;
if(!vis[g[i].v]) vis[q[t++] = g[i].v] = 1;
}
}
return (edge >> 1) == node - 1;
}

int main() {
n = iread(); m = iread();
for(int i = 0; i <= n; i++) head[i] = -1; cnt = 0;

for(int i = 1; i <= m; i++) {
int u = iread(), v = iread();
add(u, v); add(v, u);
}

bool ans = 0;
for(int i = 1; i <= n; i++) if(!vis[i]) {
ans = bfs(i);
if(ans) break;
}

printf(ans ? "NIE\n" : "TAK\n");
return 0;
}