P3370 【模板】字符串哈希

#include<bits/stdc++.h>
using namespace std;
#define int long long
typedef unsigned long long ull;
int n;
ull myhash(string s){ull code = 0, x = 131, y = 140814840257324663;for(int i = 0; i < s.size(); i++){code = (code * x + (ull)s[i]) % y;}return code;
}
void solve(){ull a[10010], ans, n;string s;cin >> n;for(int i = 0; i < n; i++){cin >> s;a[i] = myhash(s);}sort(a, a + n);ans = unique(a, a + n) - a;cout << ans << endl;
}
void solve1(){ull a = 0xffffffffffffffff;a = a / 131 - 131;cout << a << endl;while(1){int f = 0;for(ull i = 2; i <= a / i; i++){if(a % i == 0){f = 1;break;}}if(!f){cout << a << endl;return;}a--;}
}
signed main(){ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);solve();return 0;
}

P3405 [USACO16DEC] Cities and States S

#include<bits/stdc++.h>
using namespace std;
#define int long long
int n;
map<pair<int, int>, int>mp;
int myhash(string s){int code = 0;for(int i = 0; i < 2; i++){code = code * 26 + (s[i] - 'A');}return code;
}void solve(){int ans = 0, x, y;string s, c;cin >> n;for(int i = 0; i < n; i++){cin >> c >> s;x = myhash(c);y = myhash(s);if(x == y)continue; mp[{x, y}]++;ans += mp[{y, x}];}cout << ans << endl;
}signed main(){ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);solve(); return 0;
}