LeetCode Problem : Longest Common Prefix

Problem

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

Code

string longestCommonPrefix(vector<string> &strs) {
    // Note: The Solution object is instantiated only once and is reused by each test case.
    int n = strs.size();
    if(n == 0)
        return "";
    string prefix = strs[0];
    for(int i = 1; i < n; ++i){
        int j = 0;
        int m = prefix.size();
        while(j < m && strs[i][j] == prefix[j])
            ++j;
        if(j == 0)
            return "";
        prefix = prefix.substr(0,j);
    }
    return prefix;
}