【HDOJ】2266 How Many Equations Can You Find

简单DFS。

 #include <cstdio>
 #include <cstring>

 #define MAXN 15

 char str[MAXN];
 __int64 x;
 int n;

 void dfs(int s, __int64 v) {
     int i;
     __int64 tmp = ;
     if (str[s] == '\0') {
         if (v == x)
             ++n;
         return ;
     }

     for (i=s; str[i]; ++i) {
         tmp = *tmp + str[i] - '';
         dfs(i+, v+tmp);
         if (s)
             dfs(i+, v-tmp);
     }
 }

 int main() {

     while (scanf("%s %I64d", str, &x) != EOF) {
         n = ;
         dfs(, );
         printf("%d\n", n);
     }

     return ;
 }