LeetCode14-Longest Common Prefix(C++)

Description

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.

AC代碼

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        string res = "";
        if((strs.size() == 0) || (strs[0].size() == 0)){
            return res;
        }

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

        string temp = strs[0];

        for(int i=0; i<strs[0].size(); i++) {
            for(int j=1; j<strs.size(); j++) {
                if(strs[j][i] != strs[0][i]) {
                    return res;
                }
            }
            res += strs[0][i];
        }

        return res;
    }
};

測試代碼

int main() {
    Solution s;
    vector<string> a1{"flower", "flow", "flight"};
    vector<string> a2{"dog", "racecar", "car"};

    cout << "prefix of a1 is " << s.longestCommonPrefix(a1) << endl;
    cout << "prefix of a2 is " << s.longestCommonPrefix(a2) << endl;
}

總結

這一題比較簡單，做完邊界條件的判定之後，兩層for循環，一旦條件不滿足，立馬return。