Build a tiny version of the Unix uniq command. Given a list of lines, drop adjacent duplicate lines (keep only the first occurrence in each consecutive run) and return the surviving lines joined by newline characters (\n).
Function signature:
string uniq(vector<string> lines)
Example:
Input: lines = ["a", "a", "b", "c", "c", "c", "a"] Output: "a\nb\nc\na" When printed: a b c a
Notice that the trailing "a" survives because it is not adjacent to the first run of "a"s — only consecutive duplicates are removed.
Build a
vector<string> result. Push the current line only if result is empty or the line differs from result.back(). Then concatenate everything with "\n" separators.
if (result.empty() || lines[i] != result.back()) {
result.push_back(lines[i]);
}
The full solution:
class Solution {
public:
string uniq(vector<string> lines) {
vector<string> result;
for (int i = 0; i < lines.size(); i++) {
if (result.empty() || lines[i] != result.back()) {
result.push_back(lines[i]);
}
}
string out;
for (int i = 0; i < result.size(); i++) {
if (i > 0) out += "\n";
out += result[i];
}
return out;
}
};
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