dfs 写一遍

int a[10],book[10],total=0;void dfs(int step){if(step==10){if(a[1]*100+a[2]*10+a[3]+a[4]*100+a[5]*10+a[6] == a[7]*100+a[8]*10+a[9]){printf("%d%d%d + %d%d%d = %d%d%d\n",a[1],a[2],a[3],a[4],a[5],a[6],a[7],a[8],a[9]);total++;}return;}for(int i=1;i<=9;i++){if(book[i]==0){book[i]=1;a[step]=i; dfs(step+1);book[i]=0;}}}