P8827传智杯子串

KMP的典型应用,就是个模板题

值得注意的是,这个题是不区分大小写的,最开始写了一直不对,开始怀疑是不是背错模板了,最后重新读了一遍题才发现不区分大小写,所以说,深刻的教训

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认真读题!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

#include<bits/stdc++.h>
#include<unordered_map>
#define int int64_t
using namespace std;
int n, m,nxt[1000];
string s1, s2;
void getNext() {
    int pre = 0, i = 1;
    while (i < s1.size()) {
        if (s1[i] == s1[pre]) {
              pre++;
              nxt[i++] = pre;
         }
        else {
            if (pre) pre = nxt[pre - 1];
            else i++;
        }
    }
}
void solve() {
    int cnt = 0;
    cin >> n >> m >> s1 >> s2;
    for (int i = 0; i < n; ++i) s1[i] = tolower(s1[i]);
    for (int i = 0; i < m; ++i) s2[i] = tolower(s2[i]);
    memset(nxt, 0, sizeof nxt);
    getNext();
    int i = 0, j = 0;
    while (i < s2.size()) {
        if (s1[j] == s2[i])i++, j++;
        else {
            if (j) j = nxt[j - 1];
            else i++;
        }
        if (j == s1.size()) {
            cnt++;
            j = nxt[j - 1];
        }
    }
    cout << cnt << endl;
}
signed main() {
    ios::sync_with_stdio(false); cin.tie(0), cout.tie(0);
    int  t; cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}