Forem: Priyanshu srivastava

Advent of Code: Day 2

Priyanshu srivastava — Sun, 04 Dec 2022 11:14:37 +0000

Question here
Input here

The Basic thing is to note that each

win means 6 points
draw means 3 points
lose means 0 point

Part 1

Now in part 1,

A and X means rock for 1 point
B and Y means paper for 2 points
C and Z means Scissor for 3 points

import java.io.File;
import java.util.Scanner;

public class Day2 {
    public static void main(String[] args) throws Exception {
        String path = "D:\\projects\\AdventOfCode\\src\\input.txt";
        File input = new File(path);
        Scanner sc = new Scanner(input);

        int points = 0;
        while (sc.hasNextLine()) {
            var line = sc.nextLine();
            char a = line.charAt(0);
            char b = line.charAt(2);

            if (b == 'X') { // rock
                if (a == 'A') { // rock
                    points += 4;
                } else if (a == 'B') { // paper
                    points += 1;
                } else { // scissor
                    points += 7;
                }
            } else if (b == 'Y') { // paper
                if (a == 'A') { // rock
                    points += 8;
                } else if (a == 'B') { // paper
                    points += 5;
                } else { // scissor
                    points += 2;
                }
            } else { // scissor
                if (a == 'A') { // rock
                    points += 3;
                } else if (a == 'B') { // paper
                    points += 9;
                } else { // scissor
                    points += 6;
                }
            }
        }

        System.out.println(points);
        sc.close();
    }
}

Part 2

For this part,

X means lose = 0 point
Y means draw = 3 points
Z means win = 6 points

therefore we have to find the counter move for ourself according to the play by opponent i.e for eg.

if the condition is to lose and opponent plays a rock, we have to play a scissor.

import java.io.File;
import java.util.Scanner;

public class Day2 {
    public static void main(String[] args) throws Exception {
        String path = "D:\\projects\\AdventOfCode\\src\\input.txt";
        File input = new File(path);
        Scanner sc = new Scanner(input);

        int points = 0;
        while (sc.hasNextLine()) {
            var line = sc.nextLine();
            char a = line.charAt(0);
            char b = line.charAt(2);

            if (b == 'X') { // lose
                if (a == 'A') { // need scissor
                    points += 3;
                } else if (a == 'B') { // need rock
                    points += 1;
                } else { // need paper
                    points += 2;
                }
            } else if (b == 'Y') { // draw
                if (a == 'A') { // need rock
                    points += 4;
                } else if (a == 'B') { // need paper
                    points += 5;
                } else { // need scissor
                    points += 6;
                }
            } else { // win
                if (a == 'A') { // need paper
                    points += 8;
                } else if (a == 'B') { // need scissor
                    points += 9;
                } else { // need rock
                    points += 7;
                }
            }
        }

        System.out.println(points);
        sc.close();
    }
}

Advent of Code: Day 1

Priyanshu srivastava — Sun, 04 Dec 2022 07:35:49 +0000

Question here
Input here

For this puzzle we can make use of a max-heap to store the sum of calories carried by the elves in a descending order.

for part 1 of the problem we can peek the max-heap for the maximum calories

and for part 2 we can loop over the max-heap and find the sum of max-3 calories carried.

We can make use of a PriorityQueue in reverse order to make a max-head in java

import java.io.File;
import java.util.Collections;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Day1 {
    public static void main(String[] args) throws Exception {
        String path = "D:\\projects\\AdventOfCode\\src\\input.txt";
        File input = new File(path);
        Scanner sc = new Scanner(input);
        var pq = new PriorityQueue<Integer>(Collections.reverseOrder()); // max-heap
        int calories = 0;

        while (sc.hasNextLine()) {
            String calorie = sc.nextLine();
            // reset for new elf
            if (calorie.equals("")) {
                pq.offer(calories);
                calories = 0;
                continue;
            }

            calories += Integer.parseInt(calorie);
        }

        System.out.println("Result part 1 : " + pq.peek());

        int res = 0;
        for (int i = 0; i < 3; i++) {
            res += pq.poll();
        }

        System.out.println("Result part 2 : " + res);
        sc.close();
    }
}

Java Program to print something without using semi-colon

Priyanshu srivastava — Sat, 03 Dec 2022 13:21:55 +0000

In this program, we use a if statement and System.out.printf() because it returns object of PrintStream which is not null when something is passed to the printf().

public class Main {
    public static void main(String[] args) {
        if (System.out.printf("Hello World 👋") != null) {}
    }
}

whereas, System.out.println() and System.out.print() return void which cannot be used for a comparison.