字符串匹配(2)哈希匹配

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


#define MAX_N 10000
#define DEFAULT_LEN 40
char s[MAX_N + 5], t[MAX_N + 5];

#define TEST(func) {
      
       \
    char temp_s[MAX_N + 5]; \
    sprintf(temp_s, "%s(\"%s\", \"%s\") = %3d\n", #func, s, t, func(s, t)); \
    int n = DEFAULT_LEN - strlen(temp_s); \
    while (n--) printf(" "); \
    printf("%s", temp_s); \
}

int brute_one_match(const char* s, const char* t) {
    
    
    for (int j = 0; t[j]; j++) {
    
    
        if (s[j] == t[j]) continue;
        return 0;
    }
    return 1;
}

int brute_force(const char* s, const char* t) {
    
    
    for (int i = 0; s[i]; i++) {
    
    
        if (brute_one_match(s + i, t)) return i;
    }
    return -1;
}

int quick_mod(int a, int b, int c) {
    
    
    int ans = 1, temp = a;
    while (b) {
    
    
        if (b & 1) ans = ans * temp % c;
        temp = temp * temp % c;
        b >>= 1;
    }
    return ans;
}
int hash_match(const char* s, const char* t) {
    
    
    int len = strlen(t), base = 31, P = 9973, nbase = quick_mod(base, len, P);
    int h = 0, th = 0;
    for (int i = 0; t[i]; i++) th = (th * base + t[i]) % P;
    for (int i = 0; s[i]; i++) {
    
    
        h = (h * base + s[i]) % P;
        if (i >= len) h = (h - (s[i - len] * nbase % P) + P) % P;
        if (i + 1 < len) continue;
        if (h != th) continue;
        if (brute_one_match(s + i - len + 1, t)) return i - len + 1;
    }
    return -1;
}


int test_func(const char* s, const char* t) {
    
    
    return -1;
}

int main() {
    
    
    while (~scanf("%s%s", s, t)) {
    
    
        TEST(brute_force);
        TEST(test_func);
        TEST(hash_match);
    }
    return 0;
}