Problem
Programs write log files with one event per line. Each line starts with a level word followed by a space and a message, for example ERROR disk full.
Given the lines of a log file, count the lines whose first word is exactly INFO, WARNING or ERROR. Lines that start with anything else (including lowercase levels) are ignored.
Implement count_log_levels(lines).
Input
lines: The lines of the file, without line breaks.
Output
Return [info_count, warning_count, error_count].
Constraints
0 ≤ number of lines ≤ 10,000
Each line has at most 200 characters
Examples
Input:
lines = ["INFO server started", "ERROR disk full", "INFO user login", "WARNING slow query"]
Expected output:
expected = [2, 1, 1]
Input:
std::vector<std::string> lines = {"INFO server started", "ERROR disk full", "INFO user login", "WARNING slow query"};
Expected output:
std::vector<long long> expected = {2, 1, 1};
Input:
string[] lines = new string[] {"INFO server started", "ERROR disk full", "INFO user login", "WARNING slow query"};
Expected output:
long[] expected = new long[] {2, 1, 1};
Explanation
Two lines start with INFO, one with WARNING and one with ERROR: [2, 1, 1].
Input:
lines = ["info lowercase", "DEBUG details", "ERROR"]
Expected output:
expected = [0, 0, 1]
Input:
std::vector<std::string> lines = {"info lowercase", "DEBUG details", "ERROR"};
Expected output:
std::vector<long long> expected = {0, 0, 1};
Input:
string[] lines = new string[] {"info lowercase", "DEBUG details", "ERROR"};
Expected output:
long[] expected = new long[] {0, 0, 1};
Explanation
"info" is not "INFO" and DEBUG is not counted. The last line is just the word ERROR, which counts: [0, 0, 1].
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Only the first word of each line matters.
Hint 2
Split once at the first space and compare that word exactly.
Hint 3
Case matters: "info" is not "INFO", and a line can be just the level word.
Expected complexity
O(total length) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.