14.Longest Common Prefix

Tags: Easy String

Links: https://leetcode.com/problems/longest-common-prefix/

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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 "".

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Note:

All given inputs are in lowercase letters a-z.

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class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        std::ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);

        if (strs.size() == 0) return "";
        if (strs.size() == 1) return strs[0];

        int len = INT_MAX;
        int n = strs[0].size();
        int tmpLen = 0;
        for (int i = 1; i < strs.size(); ++i) {
            tmpLen = 0;
            for (int j = 0; j < strs[i].size(); ++j) {
                if (j < n && tmpLen < len && strs[0][j] == strs[i][j]) 
                    ++tmpLen;
                else break;
            }
            if (tmpLen == 0) {
                len = 0;
                break;
            }
            else len = min(tmpLen, len);
        }

        return strs[0].substr(0, len);
    }
};