ZOJ1008 Gnome Tetravex

DFS+剪枝~

#include<bits/stdc++.h>
using namespace std;
int a[][];
int N;
int cnt;
int c[];
int p[];
unordered_map<long long,int> pos;
bool dfs (int v) {
    if (v==N*N) return true;
    for (int i=;i<cnt;i++) {
        if (c[i]==) continue;
        if (v%N!=&&a[p[v-]][]!=a[i][]) continue;
        if (v/N!=&&a[p[v-N]][]!=a[i][]) continue;
        p[v]=i;
        c[i]--;
        if (dfs(v+)) return true;
        else c[i]++;
    }
    return false;
}
int main () {
    int T=;
    while (scanf("%d",&N)&&N) {
        pos.clear();
        cnt=;
        int u,d,l,r,k;
        for (int i=;i<N*N;i++) {
            scanf("%d %d %d %d",&u,&r,&d,&l);
            for (k=;k<cnt;k++) {
                if(u==a[k][]&&r==a[k][]&&d==a[k][]&&l==a[k][]) break;
            }
            if (k==cnt) {
                cnt++;
                a[k][]=u;
                a[k][]=r;
                a[k][]=d;
                a[k][]=l;
                c[k]=;
            }
            else c[k]++;
        }
        if (T!=) printf("\n");
        T++;
        if (dfs()) printf ("Game %d: Possible\n",T);
        else printf ("Game %d: Impossible\n",T);
    }
    return ;
}