[GCD] baekjoon-14476

Author: Seogeurim

README.md

@@ -20,8 +20,8 @@
 | 01  |     | [Baekjoon-2003 수들의 합 2](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P2003)   | 2-pointer                 |
 | 02  | ⭐️ | [Baekjoon-2805 나무 자르기](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P2805)   | Parametric Search         |
 | 03  | ⭐️ | [Baekjoon-2143 두 배열의 합](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P2143)  | Lower Bound & Upper Bound |
-| 03  |        | [Baekjoon-2748 피보나치 수 2](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P2748) | DP                        |
-| 03  |     | [Baekjoon-1806 부분합](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P1806)        | 2-pointer                 |
+| 04  |        | [Baekjoon-2748 피보나치 수 2](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P2748) | DP                        |
+| 05  |     | [Baekjoon-1806 부분합](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/TimeComplexity/P1806)        | 2-pointer                 |
 
 ## Data Structure
 
@@ -52,4 +52,13 @@
 | :-: | :----: | :----------------------------------------------------------------------------------------------------------------------- | :--- |
 | 01  |     | [Indexed Tree Example](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/IndexedTree/IndexedTreeTest.java) |      |
 | 02  | ⭐️ | [Baekjoon-2042 구간 합 구하기](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/IndexedTree/P2042)        |      |
-| 02  | ⭐️ | [Baekjoon-2243 사탕상자](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/IndexedTree/P2243)              |      |
+| 03  | ⭐️ | [Baekjoon-2243 사탕상자](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/IndexedTree/P2243)              |      |
+
+## Number Theory
+
+### GCD
+
+|  #  |   ☆    | Problem                                                                                                             | Note                      |
+| :-: | :----: | :------------------------------------------------------------------------------------------------------------------ | :------------------------ |
+| 01  |     | [GCD Example](https://github.com/Seogeurim/Algorithm-practice/blob/master/src/GCD/GCDTest.java) |      |
+| 02  |     | [Baekjoon-14476 최대공약수 하나 빼기](https://github.com/Seogeurim/Algorithm-practice/tree/master/src/GCD/P14476)   | 누적합                 |

src/GCD/GCDTest.java

@@ -0,0 +1,22 @@
+package GCD;
+
+public class GCDTest {
+
+    public static void main(String[] args) {
+        System.out.println("[Get GCD By Euclidean algorithm]");
+        System.out.println(gcd(132, 36));
+        System.out.println(gcd(36, 132));
+    }
+
+    static int gcd(int a, int b) {
+        System.out.println("=========================");
+        System.out.println("gcd(" + a + ", " + b + ")");
+        while (b != 0) {
+            int r = a % b;
+            a = b;
+            b = r;
+            System.out.println("gcd(" + a + ", " + b + ")");
+        }
+        return a;
+    }
+}

src/GCD/P14476/Main.java

@@ -0,0 +1,71 @@
+package GCD.P14476;
+
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class Main {
+
+    static int N;
+    static int[] nums;
+    static int answer = 0, K;
+
+    public static void main(String[] args) throws Exception {
+//        System.setIn(new FileInputStream("src/NumberTheory/gcd/P14476/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        N = Integer.parseInt(br.readLine());
+
+        nums = new int[N];
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            nums[i] = Integer.parseInt(st.nextToken());
+        }
+
+        int[] gcdLtoR = new int[N];
+        int[] gcdRtoL = new int[N];
+
+        gcdLtoR[0] = nums[0];
+        for (int i = 1; i < N; i++) {
+            gcdLtoR[i] = gcd(gcdLtoR[i-1], nums[i]);
+        }
+
+        gcdRtoL[N - 1] = nums[N - 1];
+        for (int i = N - 2; i >= 0; i--) {
+            gcdRtoL[i] = gcd(gcdRtoL[i+1], nums[i]);
+        }
+
+//        System.out.println(Arrays.toString(gcdLtoR));
+//        System.out.println(Arrays.toString(gcdRtoL));
+
+        for (int i = 0; i < N; i++) {
+            int gcd = 0;
+            if (i - 1 < 0)  {
+                gcd = gcdRtoL[i + 1];
+            } else if (i + 1 >= N) {
+                gcd = gcdLtoR[i - 1];
+            } else {
+                gcd = gcd(gcdLtoR[i - 1], gcdRtoL[i + 1]);
+            }
+            if (nums[i] % gcd != 0 && answer < gcd){
+                answer = gcd;
+                K = nums[i];
+            }
+        }
+
+        if (answer == 0) System.out.println(-1);
+        else System.out.println(answer + " " + K);
+    }
+
+    static int gcd(int a, int b) {
+        while (b != 0) {
+            int r = a % b;
+            a = b;
+            b = r;
+        }
+        return a;
+    }
+}

src/GCD/P14476/input.txt

@@ -0,0 +1,2 @@
+5
+8 12 20 32 36