[Greedy] baekjoon-2839

Author: Seogeurim

README.md

@@ -106,6 +106,12 @@
 | 11  |     | [Baekjoon-13549 숨바꼭질 3](./src/BFS/P13549)  |                          |
 | 12  | ⭐️ | [Baekjoon-20304 비밀번호 제작](./src/BFS/P20304)  |                          |
 
+## Greedy Algorithm
+
+|  #  |  ☆  | Problem                                                | Note |
+| :-: | :-: | :----------------------------------------------------- | :--- |
+| 01  |     | [Baekjoon-2839 설탕 배달](./src/Greedy/P2839)            |      |
+
 ## Data Structure
 
 ### Array

src/Greedy/P2839/Main.java

@@ -0,0 +1,18 @@
+package Greedy.P2839;
+
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int N = sc.nextInt();
+        int ans = 0;
+        while (N > 0) {
+            if (N%5==0) { ans += N/5; N = 0; }
+            else { ans ++; N-= 3; }
+        }
+        if (N < 0) System.out.println(-1);
+        else System.out.println(ans);
+    }
+}

src/Greedy/P2839/README.md

@@ -0,0 +1,11 @@
+## [baekjoon-2839] 설탕 배달
+
+![image](https://user-images.githubusercontent.com/22045163/108313759-2f0cd700-71fc-11eb-9d3f-36acbec3d89f.png)
+
+### Greedy Algorithm vs DP
+
+- [using Greedy Alg](Main.java)
+  ![image](https://user-images.githubusercontent.com/22045163/108313951-77c49000-71fc-11eb-8ec5-c4b1fb8b2e0a.png)
+
+- [using DP](usingDP.java)
+  ![image](https://user-images.githubusercontent.com/22045163/108313992-857a1580-71fc-11eb-990b-564ab4aab094.png)

src/Greedy/P2839/usingDP.java

@@ -0,0 +1,24 @@
+package Greedy.P2839;
+
+import java.util.*;
+
+public class usingDP {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        int N = sc.nextInt();
+
+        int[] dp = new int[5001];
+        Arrays.fill(dp, 5000);
+
+        dp[3] = 1;
+        dp[5] = 1;
+        for (int i = 6; i <= N; i++) {
+            dp[i] = Math.min(dp[i-3], dp[i-5]) + 1;
+        }
+
+        if (dp[N] >= 5000) System.out.println(-1);
+        else System.out.println(dp[N]);
+    }
+}