题目：

题解：

class Solution {
public:string longestCommonPrefix(vector<string>& strs) {if (!strs.size()) {return "";}int minLength = min_element(strs.begin(), strs.end(), [](const string& s, const string& t) {return s.size() < t.size();})->size();int low = 0, high = minLength;while (low < high) {int mid = (high - low + 1) / 2 + low;if (isCommonPrefix(strs, mid)) {low = mid;}else {high = mid - 1;}}return strs[0].substr(0, low);}bool isCommonPrefix(const vector<string>& strs, int length) {string str0 = strs[0].substr(0, length);int count = strs.size();for (int i = 1; i < count; ++i) {string str = strs[i];for (int j = 0; j < length; ++j) {if (str0[j] != str[j]) {return false;}}}return true;}
};