831. KMP字符串
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链接:https://www.acwing.com/problem/content/833/
\(next[i] = j\) 代表 \(p[i, j] = p[i - j + 1, j]\)
#include <iostream>
using namespace std;
const int N = 10010, M = 100010;
int n, m;
char s[M], p[N];
int ne[N];
int main() {
cin >> n >> p + 1 >> m >> s + 1;
for (int i = 2, j = 0; i <= n; ++i) {
while (j && p[i] != p[j + 1]) j = ne[j];
if (p[i] == p[j + 1]) ++j;
ne[i] = j;
}
for (int i = 1, j = 0; i <= m; ++i) {
while (j && s[i] != p[j + 1]) j = ne[j];
if (s[i] == p[j + 1]) ++j;
if (j == n) {
cout << i - n << " ";
j = ne[j];
}
}
return 0;
}
835. Trie字符串统计
#include <iostream>
using namespace std;
const int N = 100010;
int son[N][26], cnt[N], idx, n;
char str[N];
void insert(char* str) {
int p = 0;
for (int i = 0; str[i]; ++i) {
int u = str[i] - 'a';
if (!son[p][u]) son[p][u] = ++idx;
p = son[p][u];
}
cnt[p]++;
}
int query(char* str) {
int p = 0;
for (int i = 0; str[i]; ++i) {
int u = str[i] - 'a';
if (!son[p][u]) return 0;
p = son[p][u];
}
return cnt[p];
}
int main() {
cin >> n;
while (n--) {
char op[2];
scanf("%s%s", &op, &str);
if (*op == 'I') insert(str);
else cout << query(str) << endl;
}
return 0;
}