Longest Common Prefix

Problem

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

If there is no common prefix, return an empty string "".

Constraints

• 1 <= strs.length <= 200
• 0 <= strs[i].length <= 200
• strs[i] consists of only lowercase English letters.

Solution

The problem Longest Common Prefix can be solved using a vertical scanning technique through all given strings.

Implementation

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