字符串哈希

include

include

include

using namespace std;

const int N = 10010;
int n, m;
char s[N];
typedef unsigned long long ULL;
const int P = 131;
ULL h[N], ans[N];

// 计算串的哈希值
ULL calc(char s, int n){
h[0] = 0;
for(int i = 1; i <= n; i ++){
h[i] = h[i-1]P+s[i];
}
return h[n];
}

int main(){
cin >> n;
for(int i=1; i<=n; i++){
scanf("%s", s + 1);
int m = strlen(s+1);
ans[i] = calc(s, m);
}

sort(ans+1, ans+n+1);
int cnt = 0;
for(int i=1; i<=n; i++)
if(ans[i]!=ans[i-1]) ++cnt;
printf("%d", cnt);
return 0;
}//一般而言哈希值选择131或者13331，出现哈希碰撞的概率很小