KMP

1 POJ 3167 Cow Patterns

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <vector>
#include <stack>
#include <map>
#include <set>
#include <cmath>
#include <cctype>
#include <ctime>

using namespace std;

#define REP(i, n) for (int i = 0; i < (n); ++i)
#define eps 1e-9

typedef long long ll;
typedef pair<int, int> pii;

const int INF = 0x7fffffff;
const int maxn = 1e5 + 10;
int n, k, s, ans_cnt = 0;
int fail[maxn], key_p1[maxn], key_p2[maxn], a[maxn], b[maxn], cnt[40], ans[maxn];

inline int cal1(int x) {
    int ret = 0;
    for (int i = 1; i < x; ++i) { ret += cnt[i]; }
    return ret;
}
inline int cal2(int x) { return cnt[x]; }
void init() {
    for (int i = 0; i < k; ++i) {
        key_p1[i] += cal1(b[i]); key_p2[i] += cal2(b[i]); ++cnt[b[i]];
    }
}
void get_fail() {
    memset(cnt, 0, sizeof(cnt));
    fail[0] = fail[1] = 0; int j, t;
    for (int i = 1; i < k; ++i) {
        j = fail[i];
        while (j && (cal1(b[i]) != key_p1[j] || cal2(b[i]) != key_p2[j])) {
            t = j - fail[j]; j = fail[j];
            for (int i_t = 0; i_t < t; ++i_t) { --cnt[b[i - j - i_t - 1]]; }
        }
        if (key_p1[j] == cal1(b[i]) && key_p2[j] == cal2(b[i])) { fail[i + 1] = j + 1; ++cnt[b[i]]; }
        else { fail[i + 1] = 0; }
    }
}
void kmp() {
    get_fail(); int j = 0, t; memset(cnt, 0, sizeof(cnt));
    for (int i = 0; i < n; ++i) {
        while (j && (cal1(a[i]) != key_p1[j] || cal2(a[i]) != key_p2[j])) {
            t = j - fail[j]; j = fail[j];
            for (int i_t = 0; i_t < t; ++i_t) { --cnt[a[i - j - i_t - 1]]; }
        }
        if (key_p1[j] == cal1(a[i]) && key_p2[j] == cal2(a[i])) { ++j; ++cnt[a[i]]; }
        if (j == k) {
            ans[ans_cnt++] = i - k + 2;
            t = j - fail[j]; j = fail[j];
            for (int i_t = 0; i_t < t; ++i_t) {
                --cnt[a[i - j - i_t]];
            }
        }
    }
}

int main() {
#ifdef __AiR_H
    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
#endif // __AiR_H
    scanf("%d %d %d", &n, &k, &s);
    for (int i = 0; i < n; ++i) { scanf("%d", &a[i]); }
    for (int i = 0; i < k; ++i) { scanf("%d", &b[i]); }
    if (k > n) { printf("0
"); return 0; }
    init(); kmp();
    printf("%d
", ans_cnt);
    for (int i = 0; i < ans_cnt; ++i) { printf("%d
", ans[i]); }
#ifdef __AiR_H
    printf("Time used = %.2fs
", (double)clock() / CLOCKS_PER_SEC);
#endif // __AiR_H
    return 0;
}