C语言 | Leetcode C语言题解之第30题串联所有单词的子串

题目：

题解：

typedef struct {
    char key[32];
    int val;
    UT_hash_handle hh;
} HashItem;

int* findSubstring(char * s, char ** words, int wordsSize, int* returnSize){    
    int m = wordsSize, n = strlen(words[0]), ls = strlen(s);
    int *res = (int *)malloc(sizeof(int) * ls);
    int pos = 0;
    for (int i = 0; i < n; i++) {
        if (i + m * n > ls) {
            break;
        }
        HashItem *diff = NULL;
        char word[32] = {0};
        for (int j = 0; j < m; j++) {
            snprintf(word, n + 1, "%s", s + i + j * n);
            HashItem * pEntry = NULL;
            HASH_FIND_STR(diff, word, pEntry);
            if (NULL == pEntry) {
                pEntry = (HashItem *)malloc(sizeof(HashItem));
                strcpy(pEntry->key, word);
                pEntry->val = 0;
                HASH_ADD_STR(diff, key, pEntry);
            } 
            pEntry->val++;            
        }
        for (int j = 0; j < m; j++) {
            HashItem * pEntry = NULL;
            HASH_FIND_STR(diff, words[j], pEntry);
            if (NULL == pEntry) {
                pEntry = (HashItem *)malloc(sizeof(HashItem));
                strcpy(pEntry->key, words[j]);
                pEntry->val = 0;
                HASH_ADD_STR(diff, key, pEntry);
            } 
            pEntry->val--;
            if (pEntry->val == 0) {
                HASH_DEL(diff, pEntry);
                free(pEntry);
            }
        }
        for (int start = i; start < ls - m * n + 1; start += n) {
            if (start != i) {
                char word[32];
                snprintf(word, n + 1, "%s", s + start + (m - 1) * n);
                HashItem * pEntry = NULL;
                HASH_FIND_STR(diff, word, pEntry);
                if (NULL == pEntry) {
                    pEntry = (HashItem *)malloc(sizeof(HashItem));
                    strcpy(pEntry->key, word);
                    pEntry->val = 0;
                    HASH_ADD_STR(diff, key, pEntry);
                } 
                pEntry->val++;
                if (pEntry->val == 0) {
                    HASH_DEL(diff, pEntry);
                    free(pEntry);
                }
                snprintf(word, n + 1, "%s", s + start - n);
                pEntry = NULL;
                HASH_FIND_STR(diff, word, pEntry);
                if (NULL == pEntry) {
                    pEntry = (HashItem *)malloc(sizeof(HashItem));
                    strcpy(pEntry->key, word);
                    pEntry->val = 0;
                    HASH_ADD_STR(diff, key, pEntry);
                } 
                pEntry->val--;
                if (pEntry->val == 0) {
                    HASH_DEL(diff, pEntry);
                    free(pEntry);
                }
            }
            if (HASH_COUNT(diff) == 0) {
                res[pos++] = start;
            }
        }
        HashItem *curr, *tmp;
        HASH_ITER(hh, diff, curr, tmp) {
            HASH_DEL(diff, curr);  
            free(curr);      
        }
    }
    *returnSize = pos;
    return res;
}