Build a tiny version of the Unix grep command. Given a list of lines and a search pattern, return all lines that contain pattern as a substring (case-sensitive), joined by newline characters (\n).
Function signature:
string grep(vector<string> lines, string pattern)
Example:
Input: pattern = "err" lines = ["error: foo", "warning", "another error", "ok"] Output: "error: foo\nanother error" When printed: error: foo another error
If no lines match, return the empty string "".
Note: real grep treats the pattern as a regular expression by default (grep -F matches plain text). Here the pattern is always plain text: just look for it literally, so characters such as . or * mean nothing special.
Use
line.find(pattern) != string::npos to test for substring presence. Track a first flag so you only insert "\n" between matches.
The full solution:
class Solution {
public:
string grep(vector<string> lines, string pattern) {
string result;
bool first = true;
for (int i = 0; i < lines.size(); i++) {
if (lines[i].find(pattern) != string::npos) {
if (!first) result += "\n";
result += lines[i];
first = false;
}
}
return result;
}
};
Free plan: 30 tutor messages. Premium is unlimited.
Saved
Ctrl + Enter to check
