843. n-皇后问题

843. n-皇后问题 - AcWing题库

#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
using namespace std;

const int N=10;

int n;
char q[N][N];
bool col[N],dg[2*N],udg[2*N];

void dfs(int u){
    if(u==n){
        rep(i,0,n) puts(q[i]);
        puts("");
        return; 
    }
    rep(i,0,n){
        if(!col[i]&&!dg[u+i]&&!udg[n-u+i]){
            q[u][i]='Q';
            col[i]=dg[u+i]=udg[n-u+i]=true;
            dfs(u+1);
            col[i]=dg[u+i]=udg[n-u+i]=false;
            q[u][i]='.';
        }
    }
}

int main(){
    cin>>n;
    rep(i,0,n)
        rep(j,0,n)
            q[i][j]='.';
    dfs(0);
    return 0;
}

 解法二：

#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
using namespace std;

const int N=10;

int n;
char q[N][N];
bool row[N],col[N],dg[2*N],udg[2*N];

void dfs(int x,int y,int s){
    if(y==n) y=0,x++;
    if(x==n){
        if(s==n){
            rep(i,0,n) puts(q[i]);
            puts("");
        }
        return;  
    }
    dfs(x,y+1,s);
    if(!row[x]&&!col[y]&&!dg[x+y]&&!udg[x-y+n]){
        q[x][y]='Q';
        row[x]=col[y]=dg[x+y]=udg[x-y+n]=true;
        dfs(x,y+1,s+1);
        row[x]=col[y]=dg[x+y]=udg[x-y+n]=false;
        q[x][y]='.';
    }
   
}

int main(){
    cin>>n;
    rep(i,0,n)
        rep(j,0,n)
            q[i][j]='.';
    dfs(0,0,0);
    return 0;
}