Longest Common Prefix @LeetCode

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

	package leetcode.string;
	/**
	* Solution1: select first str as prefix, compare every char with second until not equals one. substring
	* loop to the last one, then we will get common prefix.
	*
	* Solution2: compare first char with every str, if works, second char...
	*
	* use j == 0 to optimize.
	*
	* @author jeffwan
	* @date Apr 15, 2014
	*/
	public class LongestCommonPrefix {
	public String longestCommonPrefix(String[] strs) {
	if (strs == null || strs.length == 0) {
	return "";
	}
	String prefix = strs[0];
	for (int i = 1; i < strs.length; i++) {
	int j = 0;
	while (j < prefix.length() && j < strs[i].length() && strs[i].charAt(j) == prefix.charAt(j)) {
	j++;
	}
	if (j == 0) {
	return "";
	}
	prefix = prefix.substring(0, j);
	}
	return prefix;
	}
	}

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