(leetcode)Longest Common Prefix

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
		int len = strs.size();
		if(len == 0) return "";
		string prefix = strs[0];
		for(int i = 1;i < len;i++)
		{
			if(prefix.length() == 0 || strs[i].length() == 0) return "";
			int slen = prefix.length() < strs[i].length() ? prefix.length():strs[i].length();
			int j;
			for(j = 0;j<slen;j++)
			{
				if(prefix[j] != strs[i][j]) break; 
			}
			prefix = prefix.substr(0,j);
		}
		return prefix;
    }
};