leetcode 459. Repeated Substring Pattern

使用KMP算法

bool kmp(char* text_str,int text_len,char*pattern_str);
bool repeatedSubstringPattern(char* s) {
    int n = strlen(s);
    char* ss = (char*)malloc(sizeof(char)*2*n+1);
    // strcpy(ss,s);
    // strcpy(ss+n,s);
    ss[0] = 0;
    strcat(ss,s);
    strcat(ss,s);
    return kmp(ss+1,2*n-2,s);
}

bool kmp(char* text_str,int text_len,char*pattern_str){
    int m = strlen(pattern_str);
    if(m == 0) true;
    int *pm = (int*) malloc(sizeof(int)*m);
    int j = 0;
    pm[0] = 0;
    for(int i = 1; i < m;i++){
        while(j > 0 && pattern_str[i] != pattern_str[j])
            j = pm[j-1];
        if(pattern_str[i] == pattern_str[j])
            j++;
        pm[i] = j;
    }

    // int n =strlen(text_str);
    int n = text_len;
    j = 0;
    for(int i = 0;i < n;i++){
        while(j > 0 && text_str[i] != pattern_str[j])
            j = pm[j-1];
        if(text_str[i] == pattern_str[j])
            j++;
        if(j == m)
            return true;
    }
    return false;
}