Longest Common Prefix

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14.Longest Common Prefix

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:

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

Example 2:

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

个人解答：

时间复杂度：O(n^2)

空间复杂度：O(1)

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string longestCommonPrefix(vector<string>& strs) {
    string ans_string = "";
    int nums_string = size(strs);//字符串的数目
    int min_lenth_string = strs[0].length();
    for (int i = 1; i < nums_string; ++i) {
        if (strs[i].length() < min_lenth_string)min_lenth_string = strs[i].length();//找到最短的字符串的长度
    }
    for (int i = 0; i < min_lenth_string; ++i) {
        for (int j = 0; j < nums_string; ++j) {
            if (strs[0][i] != strs[j][i])return ans_string;
        }
        ans_string += strs[0][i];
    }
    return ans_string;
}
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string longestCommonPerfix(vector<string> strs) {
    sort(begin(strs), end(strs));
    int size = strs.size();
    int length = min(strs[0].size(), strs[size-1].size());
    int index = 0;
    while (index < length) {
        if (strs[0][index] == strs[size-1][index]) ++index;
        else break;
    }
    return strs[0].substr(0, index);
}