zoj-1015-fishing net 【弦图的判断】

#include <cstdio>
#include <cstring>
using namespace std;
int n, m;
bool g[1024][1024], used[1024];
int lable[1024], set[1024];  //lable存储图新的编号，set存弦图计算的编号

void Relable() {
memset(used, false, sizeof(used));
used[1] = true;
for (int num=n-1; num>0; num--) {
memset(lable, 0, sizeof(lable));
for (int i=1; i<=n; i++) {
if (!used[i]) {
for (int j=1; j<=n-num; j++) {
if (g[i][set[n-j+1]])
lable[i]++;
}
}
}
int maxv = 0, max;
for (int i=1; i<=n; i++) {
if (lable[i] > maxv) {
maxv = lable[i];
max = i;
}
}
set[num] = max;
used[max] = true;
}

}
bool check() {
int temp[1024];
for (int i=1; i<=n; i++) {
memset(temp, 0, sizeof(temp));
int t = 0;
for (int j=i+1; j<=n; j++) {
if (g[set[i]][set[j]]) {
t++;
temp[t] = set[j];
}
}
for (int j=2; j<=t; j++) {
if (!g[temp[j]][temp[1]])
return false;
}
}
return true;
}
int main() {

while (scanf("%d%d", &n, &m) == 2) {
if (n == 0 && m == 0) break;
memset(g, false, sizeof(g));

int a, b;
for (int i=0; i<m; i++) {
scanf("%d%d", &a, &b);
g[a][b] = g[b][a] = true;
}
set
= 1;
Relable();
if (check()) printf("Perfect\n");
else printf("Imperfect\n");
printf("\n");
}
return 0;
}