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直接按照题意暴力就行
/*
ID: 18906421
LANG: C++
PROG: wormhole
*/
#include<cstdio>
#include<cstring>
#include<vector>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long LL;
const int maxn = 15;
LL v[maxn];
int next[maxn],connect[maxn];
int n;
int cnt = 0;
int vis2[maxn];
void debug(){
for(int i = 0; i < n; i++)
printf("%d ",next[i]);
puts("");
}
struct Point{
LL x,y;
Point(LL x = 0,LL y = 0):x(x),y(y){};
friend bool operator < (Point a,Point b){
if(a.y != b.y)
return a.y < b.y;
else
return a.x < b.x;
}
}p[maxn];
bool solve(int pos){
//printf("%d -> ",pos);
if(pos == -1)
return true;
if(vis2[next[pos]])
return false;
if(next[pos] == -1)
return true;
vis2[next[pos]] = 1;
return solve(connect[next[pos]]);
}
bool judge(){
for(int i = 0; i < n; i++){
memset(vis2,0,sizeof(vis2));
vis2[i] = 1;
//printf("%d %d\n",i,connect[i]);
bool ok = solve(connect[i]); //puts("");
if(!ok){
//printf("[%d]\n",i);
return false;
}
}
return true;
}
void dfs(int pos){
if(pos == n){
if(!judge()){
//for(int i = 0; i < n; i++) printf("[%d] %d ",i,connect[i]); puts("");
cnt ++;
}
return;
}
if(connect[pos] == -1)
for(int i = 0; i < n; i++){
if(connect[i] == -1 && i != pos){
connect[pos] = i;
connect[i] = pos;
dfs(pos + 1);
connect[i] = -1;
connect[pos] = -1;
}
}
else
dfs(pos + 1);
}
int main(){
//freopen("wormhole.in","r",stdin);
//freopen("wormhole.out","w",stdout);
cin >> n;
for(int i = 0; i < n; i++){
cin >> p[i].x >> p[i].y;
next[i] = -1;
connect[i] = -1;
}
sort(p,p + n);
for(int i = 0; i < n - 1; i++)
if(p[i].y == p[i + 1].y)
next[i] = i + 1;
//debug();
dfs(0);
printf("%d\n",cnt);
return 0;
}
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原文地址：http://blog.csdn.net/u013451221/article/details/45032883
