模板库（字符串相关）

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字符串哈希

#include<cstdio>#include<algorithm>#include<cstring>typedef long long ll;using namespace std;const int N = 10000 + 10;const int base = 29;const int mod1 = 1e9+7;const int mod2 = 19260817;int n; char s[N];ll q_pow(ll a, int p, ll mod) {    if(p == 0) return 1;    ll ret = 1;    for(; p; p >>= 1) {        if(p&1) ret = ret*a%mod;        a = a*a%mod;    }    return ret;}struct Hash {    ll x, y;}hash[N];ll pow[2][1510];bool cmp(const Hash& a, const Hash& b) {    if(a.x == b.x) return a.y < b.y;    return a.x < b.x;}void pre() {    pow[0][0] = pow[1][0] = 1;    for(int i = 1; i <= 1500; ++i) {        pow[0][i] = pow[0][i-1]*base%mod1;        pow[1][i] = pow[1][i-1]*base%mod2;    }}int main() {    pre();    scanf("%d", &n);    for(int i = 1; i <= n; ++i) {        scanf("%s", s);        int len = strlen(s);        for(int j = 0; j < len; ++j) {            hash[i].x += pow[0][j]*((int)(s[j]))%mod1;            hash[i].y += pow[1][j]*((int)(s[j]))%mod2;        }    }    sort(hash+1, hash+n+1, cmp);    int ans = 1;    for(int i = 1; i < n; ++i) {        while(hash[i].x == hash[i+1].x && hash[i].y == hash[i+1].y) i++;        if(i == n) break;        ans++;    }    printf("%d\n", ans);    return 0;}

KMP（正儿八经）

#include<cstdio>#include<cstring>const int N = 1e6 + 10;char s[N], t[N];int nxt[N], slen, tlen;void get_nxt() {    nxt[1] = 0;    for(int i = 2; i <= tlen; ++i) {        int j = nxt[i-1];        while(j && t[j+1] != t[i]) j = nxt[j];        if(t[j+1] == t[i]) ++j;        nxt[i] = j;    }}void match() {    int j = 0;    for(int i = 1; i <= slen; ++i) {        while(j > 0 && t[j+1] != s[i]) j = nxt[j];        if(t[j+1] == s[i]) j++;        if(j == tlen) {            printf("%d\n", i-tlen+1);            j = nxt[j];        }    }}int main() {    scanf("%s%s", s+1, t+1);    slen = strlen(s+1); tlen = strlen(t+1);    get_nxt();    match();    for(int i = 1; i <= tlen; ++i) printf("%d ", nxt[i]);    return 0;}

strstr

#include<cstdio>#include<cstring>using namespace std;const int N = 1e6 + 10;char s[N], t[N];int main() {    scanf("%s%s", s+1, t+1);    int pos = 0;    while(strstr(s+1+pos, t+1) != NULL) {        pos = strstr(s+1+pos, t+1) - s;        printf("%d\n", pos);    }     return 0;}

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