C/C++编程小练习 数独(DFS算法实现)

数独(DFS算法实现)

代码:

#include <cstdio>#include <cstdlib>int test[9][9]={0,0,5,3,0,0,0,0,0,8,0,0,0,0,1,0,2,0,0,7,0,0,1,0,5,0,0,4,0,0,0,0,5,3,0,0,0,1,0,0,7,0,0,0,6,0,0,3,2,9,0,0,8,0,0,6,0,5,0,0,0,0,9,0,0,0,0,0,0,0,3,0,0,0,0,0,0,9,7,0,0};int mark[9][9];bool flag=true;bool ok=false;int cnt;void dfs(int m,int n);int main(){    for(int i=0;i<9;++i){        for(int j=0;j<9;++j){            if(test[i][j]!=0){                mark[i][j]=1;            }        }    }dfs(0,0);return 0;}void dfs(int m,int n){    if(ok==true){        return;    }    if(m==8&&n==9){//边界        printf("%d:\n",++cnt);        for(int i=0;i<9;++i){            for(int j=0;j<9;++j){                printf("%d ",test[i][j]);            }            printf("\n");        }        printf("\n");        ok=true;        return;    }else{        if(n==9){//一行到了边界            dfs(m+1,0);            return ;        }        if(mark[m][n]==1){//若填过了            dfs(m,n+1);//跳到下一格            return;        }        for(int i=1;i<=9;++i){            for(int x=0;x<9;++x){                for(int y=0;y<9;++y){                    if(mark[m][y]==1&&test[m][y]==i||                       mark[x][n]==1&&test[x][n]==i){                        flag=false;                        goto X;                    }                }            }            if(flag==true){                mark[m][n]=1;                test[m][n]=i;                dfs(m,n+1);                mark[m][n]=0;            }            X: //这里输出一个解后就跳出了,把goto去掉会生成所有解            flag=true;        }    }}

运行结果会生成多个解(去掉goto)