[LeetCode 14] Longest Common Prefix [C] [Runtime : 3 MS]

1. Description

Write a function to find the longest common prefix string amongst an array of strings.

2. Example

{"a","a","b"} should give "" as there is nothing common in all the 3 strings.
{"a", "a"} should give "a" as a is longest common prefix in all the strings.
{"abca", "abc"} as abc
{"ac", "ac", "a", "a"} as a

3. Code

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char* longestCommonPrefix(char** strs, int strsSize) {

	int str0_length = strsSize == 0 ? 0 : strlen(strs[0]);

	int i = 0, is_find = 0;
	for (; i < str0_length && !is_find; i++ ) 
	{
		for (int j = 1; j < strsSize && !is_find; j++) 
		{
			if (strs[0][i] != strs[j][i]) 
			{
				i--; is_find = 1;
			}
		}
	}

	char *result = (char*)malloc((i + 1) * sizeof(char));
	strncpy(result, strs[0], i);
	result[i] = '\0';
	return result;
}

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4.Test

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#include

char* longestCommonPrefix(char** strs, int strsSize) {

	int str0_length = strsSize == 0 ? 0 : strlen(strs[0]);

	int i = 0, is_find = 0;
	for (; i < str0_length && !is_find; i++ ) 
	{
		for (int j = 1; j < strsSize && !is_find; j++) 
		{
			if (strs[0][i] != strs[j][i]) 
			{
				i--; is_find = 1;
			}
		}
	}

	char *result = (char*)malloc((i + 1) * sizeof(char));
	strncpy(result, strs[0], i);
	result[i] = '\0';
	return result;
}

int main()
{
	char *strs[] = { "a","b" };
	puts(longestCommonPrefix(strs, 2));
	system("pause");
	return 0;
}

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