[LeetCode]32. Longest Common Prefix最长公共前缀

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

解法：从所有的string的头到尾的字母逐一比较即可。

class Solution {
public:
string longestCommonPrefix(vector<string>& strs) {
int n = strs.size(), i = 0;
bool flag = false;
if (n == 0) return string("");
if (n == 1) return strs[0];
while (true)
{
for (int j = 0; j < n - 1; j++)
{
if (i >= strs[j].size() || strs[j][i] != strs[j + 1][i])
{
flag = true;
break;
}
}
if (flag) break;
i++;
}
return string(strs[0].begin(), strs[0].begin() + i);
}
};

精简得到一个更简洁的代码版本：

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