poj 2785 hash

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <algorithm>
 5 #include <set>
 6 #include <vector>
 7 
 8 using namespace std;
 9 
10 #define MAX 1000000000
11 #define size 20345677
12 #define key 745
13 
14 int hash[size],sum[size];
15 
16 void hash_insert(int num) {
17     int tmp = num;
18     num = (num + MAX)%size;
19     while(hash[num]!=MAX&&hash[num]!=tmp) {
20         num = (num + key)%size;
21     }
22     hash[num] = tmp;
23     sum[num]++;
24 }
25 
26 int hash_Find(int num) {
27     int tmp = num;
28     num = (num + MAX)%size;
29     while(hash[num]!=MAX&&hash[num]!=tmp) {
30         num = (num + key)%size;
31     }
32     if(hash[num]==MAX) return 0;
33     return sum[num];
34 }
35 
36 int a[4040],b[4040],c[4040],d[4040];
37 
38 int main() {
39     int n;
40     scanf("%d",&n);
41 
42     for(int i=0; i<size; i++)
43         hash[i] = MAX;
44     memset(sum,0,sizeof(sum));
45 
46     for(int i=0; i<n; i++) {
47         scanf("%d%d%d%d",&a[i],&b[i],&c[i],&d[i]);
48     }
49 
50     for(int i=0; i<n; i++) {
51         for(int j=0; j<n; j++) {
52             hash_insert(a[i]+b[j]);
53         }
54     }
55 
56     int ans = 0;
57     for(int i=0; i<n; i++) {
58         for(int j=0; j<n; j++) {
59             ans+=hash_Find(-(c[i]+d[j]));
60         }
61     }
62 
63     cout<<ans<<endl;
64     return 0;
65 }