快速哈希表

  1 #include <cstdio>
  2 #include <iostream>
  3 #include <algorithm>
  4 #include <cstring>
  5 #include <cmath>
  6 #define REP(s, n) for(int i = s; i <= n; i ++)
  7 using namespace std;
  8 const int maxn = 2000 + 10;
  9 const int hash_max = 5677913;
 10 const int hash_check = 2787907;
 11 const int hash_delta = 2890003;
 12 const int hash_find = 40009;
 13 const int inf = 1000000001;
 14 int hash[hash_max];
 15 bool vis[hash_max];
 16 int hash_sortn(int v){
 17     v %= hash_max;
 18     if(v < 0) v += hash_max;
 19     return v;
 20 }
 21 int hash_checkn(int v){
 22     if(v & 1) { v = v % hash_check; if(v < 0) v += hash_check; }
 23     else { v = v % hash_check; if(v < 0) v += hash_check; v += hash_delta; }
 24     return v;
 25 }
 26 int hash_findn(int v){
 27     v = (v * hash_find) % hash_max;
 28     if(v < 0) v += hash_max;
 29     return v;
 30 }
 31 int find_insert(int v){
 32     int ids = hash_sortn(v);
 33     if(!vis[ids]){              //一致性探查 
 34         hash[ids] = v;
 35         vis[ids] = true;
 36         return ids;
 37     }
 38     else if(v == hash[ids]) return inf;
 39     int id = hash_checkn(v);
 40     if(!vis[id]){              //二次奇偶性探查 
 41         hash[id] = v;
 42         vis[id] = true;
 43         return id;
 44     }
 45     for(int i = id; ; i += hash_findn(i) + ids * i){  //完全性探查 
 46         i %= hash_max;
 47         if(i < 0) i += hash_max;
 48         if(!vis[i]){              //二次奇偶性探查 
 49             hash[i] = v;
 50             vis[i] = true;
 51             return i;
 52         }
 53         else if(v == hash[i]) return inf;
 54     }
 55 }
 56 bool find(int v){
 57     int ids = hash_sortn(v);
 58     if(!vis[ids]) return false;
 59     if(hash[ids] == v) return true;
 60     int id = hash_checkn(v);
 61     if(!vis[id]) return false;
 62     if(hash[id] == v) return true;
 63     for(int i = id; ; i += hash_findn(i) + ids * i){  //完全性探查 
 64         i %= hash_max;
 65         if(i < 0) i += hash_max;
 66         if(!vis[i]) return false;
 67         else if(v == hash[i]) return true;
 68     }
 69 }
 70 int b[maxn], c[maxn], d[maxn], n;
 71 bool check(int v){
 72     for(int i = n; i; i --){
 73         int temp = v - b[i];
 74         for(int j = n; j; j --){
 75             if(find(temp - c[j])) return true;
 76         }
 77     }
 78     return false;
 79 }
 80 void read(int &x){
 81     x = 0; int sig = 1; char ch = getchar();
 82     while(!isdigit(ch)) { if(ch == ‘-‘) sig = -1; ch = getchar(); }
 83     while(isdigit(ch)) x = 10 * x + ch - ‘0‘, ch = getchar();
 84     x *= sig; return ;
 85 }
 86 void init(){
 87     read(n);
 88     int temp;
 89     REP(1, n) read(temp), find_insert(temp);
 90     REP(1, n) read(b[i]);
 91     REP(1, n) read(c[i]);
 92     REP(1, n) read(d[i]);
 93     sort(d + 1, d + 1 + n);
 94     sort(c + 1, c + 1 + n);
 95     sort(b + 1, b + 1 + n);
 96     return ;
 97 }
 98 int ans = 2000000000;
 99 void work(){
100     for(int i = n; i; i --){
101         if(check(d[i])) { ans = d[i]; return ; } 
102     }
103     return ;
104 }
105 void print(){
106     if(ans == 2000000000) puts("No Answer.");
107     else printf("%d\n", ans);
108     return ;
109 }
110 int main(){
111     init();
112     work();
113     print();
114     return 0;
115 }