Keyboard Row

https://leetcode.com/problems/keyboard-row/?tab=Description

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

Example 1:

Input: ["Hello", "Alaska", "Dad", "Peace"]Output: ["Alaska", "Dad"]

Note:

1. You may use one character in the keyboard more than once.
2. You may assume the input string will only contain letters of alphabet.

/** * Return an array of size *returnSize. * Note: The returned array must be malloced, assume caller calls free(). */char** findWords(char** words, int wordsSize, int* returnSize) {    static char a[256] = {        ['q'] = 1, ['Q'] = 1,        ['w'] = 1, ['W'] = 1,        ['e'] = 1, ['E'] = 1,        ['r'] = 1, ['R'] = 1,        ['t'] = 1, ['T'] = 1,        ['y'] = 1, ['Y'] = 1,        ['u'] = 1, ['U'] = 1,        ['i'] = 1, ['I'] = 1,        ['o'] = 1, ['O'] = 1,        ['p'] = 1, ['P'] = 1,                ['a'] = 2, ['A'] = 2,        ['s'] = 2, ['S'] = 2,        ['d'] = 2, ['D'] = 2,        ['f'] = 2, ['F'] = 2,        ['g'] = 2, ['G'] = 2,        ['h'] = 2, ['H'] = 2,        ['j'] = 2, ['J'] = 2,        ['k'] = 2, ['K'] = 2,        ['l'] = 2, ['L'] = 2,                ['z'] = 3, ['Z'] = 3,        ['x'] = 3, ['X'] = 3,        ['c'] = 3, ['C'] = 3,        ['v'] = 3, ['V'] = 3,        ['b'] = 3, ['B'] = 3,        ['n'] = 3, ['N'] = 3,        ['m'] = 3, ['M'] = 3,    };        char **res = (char*)malloc(sizeof(char*)*wordsSize);    int cur = 0;    int j,len;    for(int i = 0; i < wordsSize; i++){        len = strlen(words[i]);        for(j = 1; j < len; j++) {            if(a[words[i][j]] != a[words[i][j-1]]) break;        }        if(j == len || len == 0) {            res[cur] = malloc(len+1);            strcpy(res[cur++], words[i]);        }    }    *returnSize = cur;    return res;}