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Commit 2c0bdaf

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day01 for AoC 2023 (part 2)
Took 10 minutes
1 parent 488b972 commit 2c0bdaf

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2 files changed

+28
-8
lines changed

2 files changed

+28
-8
lines changed

‎src/main/java/aminetti/adventofcode2024/day01/Day01.java

Lines changed: 25 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -4,10 +4,10 @@
44
import org.slf4j.Logger;
55
import org.slf4j.LoggerFactory;
66

7-
import java.math.BigInteger;
8-
import java.sql.Array;
97
import java.util.ArrayList;
8+
import java.util.HashMap;
109
import java.util.List;
10+
import java.util.Map;
1111
import java.util.regex.Matcher;
1212
import java.util.regex.Pattern;
1313

@@ -33,7 +33,7 @@ public long solvePart1() {
3333
if (matcher.matches()) {
3434
Integer a = Integer.valueOf(matcher.group(1));
3535
Integer b = Integer.valueOf(matcher.group(2));
36-
LOGGER.info("Reading: {} and {}", a ,b);
36+
LOGGER.info("Reading: {} and {}", a, b);
3737
left.add(a);
3838
right.add(b);
3939
} else {
@@ -42,11 +42,31 @@ public long solvePart1() {
4242
}
4343

4444
return Streams.zip(left.stream().sorted(), right.stream().sorted(),
45-
(a, b) -> Math.abs(a-b)).reduce(0, (a, b) -> a + b);
45+
(a, b) -> Math.abs(a - b)).reduce(0, Integer::sum);
4646
}
4747

4848
public long solvePart2() {
49+
Pattern p = Pattern.compile("(\\d+)\\s+(\\d+)");
50+
51+
Map<Long, Long> left = new HashMap<>(input.size());
52+
Map<Long, Long> right = new HashMap<>(input.size());
53+
54+
for (String s : input) {
55+
Matcher matcher = p.matcher(s);
56+
if (matcher.matches()) {
57+
Long a = Long.valueOf(matcher.group(1));
58+
Long b = Long.valueOf(matcher.group(2));
59+
LOGGER.info("Reading: {} and {}", a, b);
60+
left.compute(a, (k, v) -> (v == null) ? 1 : v + 1);
61+
right.compute(b, (k, v) -> (v == null) ? 1 : v + 1);
62+
} else {
63+
throw new IllegalArgumentException("Invalid input: " + s);
64+
}
65+
66+
}
4967

50-
return 0;
68+
return left.keySet().stream().
69+
map((k) -> k * left.get(k) * right.getOrDefault(k, 0L))
70+
.reduce(0L, Long::sum);
5171
}
5272
}

‎src/test/java/aminetti/adventofcode2024/day01/Day01Test.java

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -24,7 +24,7 @@ void actualInputPart1() throws IOException {
2424
long l = solver.solvePart1();
2525

2626
// then
27-
assertThat(l, is(110396520L));
27+
assertThat(l, is(1889772L));
2828
}
2929

3030
@Test
@@ -52,7 +52,7 @@ void actualInputPart2() throws IOException {
5252
long l = solver.solvePart2();
5353

5454
// then
55-
assertThat(l, is(11L));
55+
assertThat(l, is(23228917L));
5656
}
5757

5858
@Test
@@ -66,7 +66,7 @@ void testInputPart2() throws IOException {
6666
long l = solver.solvePart2();
6767

6868
// then
69-
assertThat(l, is(0L));
69+
assertThat(l, is(31L));
7070
}
7171

7272

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