蓝桥杯省赛-2016-C/C++-B-7

状态压缩枚举

#include<bits/stdc++.h>
using namespace std;
#define LOCAL
#define ll long long int
#define inf 0x3f3f3f3f
#define mset(a,b) memset(a,b,sizeof(a))
const int maxn=1e5+5;
int a[12];
int g[3][4];
bool check(int x){
    int ans=0;
    while(x){
        ans+=x&1;
        x>>=1;
    }
    return ans==5;
}
void dfs(int i,int j){
    g[i][j]=0;
    if(i-1>=0&&g[i-1][j]) dfs(i-1,j);
    if(i+1<3&&g[i+1][j]) dfs(i+1,j);
    if(j-1>=0&&g[i][j-1]) dfs(i,j-1);
    if(j+1<4&&g[i][j+1]) dfs(i,j+1);
}
bool f(int z){
    for(int i=0;i<3;i++){
        for(int j=0;j<4;j++){
            g[i][j]=z&1;
            z>>=1;
        }
    }
    int cnt=0;
    for(int i=0;i<3;i++){
        for(int j=0;j<4;j++){
            if(g[i][j]){
                dfs(i,j);
                cnt++;
            }
        }
    }
    return cnt==1;
}
void solve(){
    int len=pow(2,12);
    int ans=0;
    for(int i=0;i<len;i++){
        if(check(i)&&f(i)){
            ans++;
        }
    }
    printf("%d",ans);
}
int main(){
#ifdef LOCAL
    freopen("in.in","r",stdin);
#endif
    solve();
    return 0;
}
Author: universal42
Link: https://universal4s.github.io/2019/03/17/trashed/
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