Add: algorithm of baekjoon

Author: ImSejin

src/main/java/io/github/imsejin/study/baekjoon/bronze/P1373.java

@@ -0,0 +1,55 @@
+package io.github.imsejin.study.baekjoon.bronze;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.math.BigInteger;
+
+public class P1373 {
+
+    public static void main(String[] args) throws Exception {
+        try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
+            String binary = reader.readLine();
+
+            String answer = solve1(binary);
+            System.out.println(answer);
+        }
+    }
+
+    static String solve1(String binary) {
+        if (binary.equals("0")) return "0";
+
+        int length = binary.length();
+        StringBuilder sb = new StringBuilder();
+
+        int bit = 0;
+        for (int i = 1; i <= length; i++) {
+            char c = binary.charAt(length - i);
+
+            int r = i % 3;
+            if (c == '1') {
+                int b = switch (r) {
+                    case 1 -> 1;
+                    case 2 -> 2;
+                    case 0 -> 4;
+                    default -> throw new IllegalArgumentException();
+                };
+
+                bit += b;
+            }
+
+            if (r == 0) {
+                sb.append(bit);
+                bit = 0;
+            }
+        }
+
+        if (bit > 0) sb.append(bit);
+
+        return sb.reverse().toString();
+    }
+
+    static String solve2(String binary) {
+        return new BigInteger(binary, 2).toString(8);
+    }
+
+}

src/test/groovy/io/github/imsejin/study/baekjoon/bronze/P1373Spec.groovy

@@ -0,0 +1,24 @@
+package io.github.imsejin.study.baekjoon.bronze
+
+import spock.lang.Specification
+
+class P1373Spec extends Specification {
+
+    def "test"() {
+        when:
+        def actual = P1373.solve1(binary)
+
+        then:
+        actual == octal
+        actual == P1373.solve2(binary)
+
+        where:
+        binary     | octal
+        "0"        | "0"
+        "111"      | "7"
+        "1000"     | "10"
+        "1010"     | "12"
+        "11001100" | "314"
+    }
+
+}