HDU5183 hash 表

做题的时候忘了 数据结构老师说的hash表了， 用二分找，还好过了， hash 表 对这题 更快一些

 #include <iostream>
 #include <algorithm>
 #include <string.h>
 #include <cstdio>
 #include <set>
 using namespace std;
 const int maxn =+;
 typedef long long LL;
 const int MAXN=;
 const int HASH=;
 inline LL read()
 {
     char ch=getchar();LL x=,f=;
     while(ch>''||ch<''){if(ch=='-')f=-;ch=getchar();}
     while(ch<=''&&ch>=''){x=x*+ch-'';ch=getchar();}
     return x*f;
 }
 struct HASHMAP
 {
     int head[HASH],next[MAXN],size;
     LL state[MAXN];
     void init()
     {
         size=;
         memset(head,-,sizeof(head));
     }
     bool check(LL val)
     {
         int h=(val%HASH+HASH)%HASH;
         for(int i=head[h];~i;i=next[i])
             if(state[i]==val)return true;
         return false;
     }
     int insert(LL val)
     {
         int h=(val%HASH+HASH)%HASH;
         for(int i=head[h];~i;i=next[i])
         {
             if(val==state[i])
                 return ;
         }
         state[size]=val;
         next[size]=head[h];
         head[h]=size++;
         return ;
     }
 }H1;
 LL A[maxn];
 LL sum[maxn];
 int main()
 {
     int cas;
     scanf("%d",&cas);
     for(int cc =; cc<=cas; ++cc){
         int n;
         LL K;
         scanf("%d%I64d",&n,&K);
         bool falg=false;
         for(int i=; i<n; ++i){
             scanf("%I64d",&A[i]);
             if(K==A[i])falg=true;
         }
         printf("Case #%d: ",cc);
         if(falg){
                 printf("Yes.\n"); continue;
         }
             H1.init();
         sum[n]=; LL sig=;
         LL to;
         for(int i=n-; i>=; i--){
                 sum[i]=sum[ i+ ]+A[ i ]*sig;
               if(sig==){
                  to = sum[i]-K;
                  if(H1.check(to)){
                      falg=true ; break;
                  }
               } else{
                  to= -(-sum[i]-K);
                  if(H1.check(to)){
                      falg=true ; break;
                  }
               }
               sig*=-;
               H1.insert(sum[i]);
         }
         if(falg)
             printf("Yes.\n");
          else printf("No.\n");
     }

     return ;
 }