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A Java Starter Template for competitive programming in CodeChef, Hackerrank, etc w/ efficient coding rules and pre-designed pattern Ready to Use
/*
* No package must be added here because some Online Judges don't support it
* please remove, if any.
*
*/
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/*
* Only classes with 'Main' name are accepted in CodeChef and some other online judges
*/
public class Main {
/*
* In a Programming contest, you are expected to print the output at the
* end, so `output` variable will hold all the processed results till the
* end
*/
public static String output = "";
// Program's starting point
public static void main(String[] args) {
/*
* A Scanner class slows down Input/Output a LOT ,thereby increasing
* your code execution time , Hence for best results that is Fast I/O
* try to use BufferedReader
*/
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
/*
* Generally Code Chef, Hacker Rank gives X number of test cases so we
* process the input for each.
*/
final int cases;
try {
cases = Integer.parseInt(br.readLine().trim());
/*
* Logic of the program must be separated from the meta code to
* increase readability and help debugging easier
* Also note that Solver object is created inside for loop to
* avoid multiple object creation that drastically increases
* execution time and memory usage
*/
Solver solver = new Solver();
for (int i = 0; i < cases; i++) {
solver.solve(br.readLine());
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// Print the final output
System.out.println(output);
}
}
/*
* Some basic rules while coding in Programming Contests:
* Try to follow at least 80% of them
Correctness
- final declaration for required data types
- avoid Object creation
- Scanner slows down, use InputReader
- avoid too many static functions
Efficiency
- use library functions as much as possible
- assertEquals("RESULT", functionToCall())
Debugging-ability
- avoid too many global variables
- Separate logic from meta-processing
- variable/function pneumonics must make sense
*
*/
class Solver {
/*
* Logic goes here ...
* Add to the global variables after processing the input
* Maybe reverse a string or parse to an integer or , etc.
*/
public void solve(String input) {
Main.output.concat(input);
}
}
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