把每一列能射的两行和这一列连边，然后跑一边匈牙利就行了。
#include <cstdio>
#include <cstring>
#include <algorithm>
using std::swap;
#define Open(s) freopen(s".in","r",stdin);freopen(s".out","w",stdout);
#define Close fclose(stdin);fclose(stdout);
inline int read(){
int s = 0;
char ch = getchar();
while(ch < '0' || ch > '9') ch = getchar();
while(ch >= '0' && ch <= '9'){ s = s * 10 + ch - '0'; ch = getchar(); }
return s;
}
const int MAXN = 2010;
int T, n, m, a[MAXN], b[MAXN], flag[MAXN], match[MAXN], c[MAXN], ans;
struct Edge{
int next, to;
}e[MAXN << 1];
int head[MAXN], num;
inline void Add(int from, int to){
e[++num].to = to;
e[num].next = head[from];
head[from] = num;
}
void print(){
for(int i = 1; i <= m; ++i){
if(!match[i]) match[i] = a[i];
printf("%d ", match[i]);
}
puts("");
}
int find(int x){
for(int i = head[x]; i; i = e[i].next)
if(!flag[e[i].to]){
flag[e[i].to] = 1;
if(!match[e[i].to] || find(match[e[i].to])){
match[e[i].to] = x;
return 1;
}
}
return 0;
}
int Judge(){
for(int i = 1; i <= m; ++i)
c[match[i]] = T;
for(int i = 1; i <= n; ++i)
if(c[i] != T)
return 1;
return 0;
}
int main(){
Open("she");
T = read() + 1;
while(--T){
num = 0; for(int i = 1; i <= (m << 1); ++i) head[i] = 0;
n = read(); m = read();
for(int i = 1; i <= m; ++i){
a[i] = read(); b[i] = read();
Add(a[i], i); Add(b[i], i);
match[i] = 0;
}
for(int i = 1; i <= n; ++i){
for(int i = 1; i <= m; ++i)
flag[i] = 0;
find(i);
}
if(Judge()) printf("NO
");
else print();
}
return 0;
}