【HDOJ】3325 Arithmetically Challenged

简单DFS。

 /* 3325 */
 #include <iostream>
 #include <set>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 using namespace std;

 #define MAXN 100005
 #define INF 0x3f3f3f3f

 int buf[MAXN];
 int a[];
 set<int> S;
 set<int>::iterator iter;

 int cal(int a, int b, int op) {
     if (op == )    return a+b;
     if (op == )    return a-b;
     if (op == )    return a*b;
     if (op == )    return (b==||a%b) ? INF:a/b;
     return INF;
 }

 void f() {
     int i, j, k;
     int tmp1, tmp2;
     int ans;

     //((AB)C)D (AB) (CD)
     for (i=; i<; ++i) {
         tmp1 = cal(a[], a[], i);
         if (tmp1 == INF)
             continue;
         for (j=; j<; ++j) {
             tmp2 = cal(tmp1, a[], j);
             if (tmp2 != INF) {
                 for (k=; k<; ++k) {
                     ans = cal(tmp2, a[], k);
                     if (ans != INF)
                         S.insert(ans);
                 }
             }
             tmp2 = cal(a[], a[], j);
             if (tmp2 != INF) {
                 for (k=; k<; ++k) {
                     ans = cal(tmp1, tmp2, k);
                     if (ans != INF)
                         S.insert(ans);
                 }
             }
         }
     }

     // (A(BC))D A((BC)D)
     for (i=; i<; ++i) {
         tmp1 = cal(a[], a[], i);
         if (tmp1 == INF)
             continue;
         for (j=; j<; ++j) {
             tmp2 = cal(a[], tmp1, j);
             if (tmp2 != INF) {
                 for (k=; k<; ++k) {
                     ans = cal(tmp2, a[], k);
                     if (ans != INF)
                         S.insert(ans);
                 }
             }
             tmp2 = cal(tmp1, a[], j);
             if (tmp2 != INF) {
                 for (k=; k<; ++k) {
                     ans = cal(a[], tmp2, k);
                     if (ans != INF)
                         S.insert(ans);
                 }
             }
         }
     }

     // A(B(CD))
     for (i=; i<; ++i) {
         tmp1 = cal(a[], a[], i);
         if (tmp1 == INF)
             continue;
         for (j=; j<; ++j) {
             tmp2 = cal(a[], tmp1, j);
             if (tmp2 != INF) {
                 for (k=; k<; ++k) {
                     ans = cal(a[], tmp2, k);
                     if (ans != INF)
                         S.insert(ans);
                 }
             }
         }
     }
 }

 int main() {
     int t = , n;
     int i, j, k;
     int ans;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     while (scanf("%d%d%d%d",&a[],&a[],&a[],&a[])!=EOF && (a[]+a[]+a[]+a[])) {
         S.clear();
         sort(a, a+);
         do {
             f();
         } while (next_permutation(a, a+));
         n =;
         for (iter=S.begin(); iter!=S.end(); ++iter)
             buf[n++] = *iter;
         ans = k = ;
         for (i=; i<n; ++i) {
             if (buf[i]==buf[i-]+)
                 ++k;
             else
                 k = ;
             if (ans <= k) {
                 ans = k;
                 j = buf[i];
             }
         }
         printf("Case %d: %d to %d\n", ++t, j-ans, j);
     }

     return ;
 }