[dfs基础]XXX+XXX=XXX

#include<cstdio>using namespace std;int a[10],book[10],sum=0;void dfs(int step){int i;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]){sum++;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]);}return;}for(i=1;i<=9;i++){if(book[i]==0){a[step]=i;book[i]=1;dfs(step+1);book[i]=0;}}return;}int main(){dfs(1);printf("The sum of all way is %d",sum/2);return 0;}