비교코드 추가

KSH-code · KSH-code · commit 23f2e23a0bc9 · 2017-10-27T14:12:11.000+09:00
diff --git a/src/test/java/algorithm/recursion/Dice.java b/src/test/java/algorithm/recursion/Dice.java
@@ -14,23 +14,45 @@ public class Dice {
 
     @Test
     public void test() {
-        assertThat(calcDiceCase(3), is(4));
-        assertThat(calcDiceCase(4), is(8));
-        assertThat(calcDiceCase(5), is(16));
-        assertThat(calcDiceCase(6), is(32));
-        assertThat(calcDiceCase(7), is(63));
-        assertThat(calcDiceCase(8), is(125));
+        assertThat(calcDiceCase1(3), is(4));
+        assertThat(calcDiceCase1(4), is(8));
+        assertThat(calcDiceCase1(5), is(16));
+        assertThat(calcDiceCase1(6), is(32));
+        assertThat(calcDiceCase1(7), is(63));
+        assertThat(calcDiceCase1(8), is(125));
+        assertThat(calcDiceCase1(3), is(4));
+
+        assertThat(calcDiceCase2(4), is(8));
+        assertThat(calcDiceCase2(5), is(16));
+        assertThat(calcDiceCase2(6), is(32));
+        assertThat(calcDiceCase2(7), is(63));
+        assertThat(calcDiceCase2(8), is(125));
     }
 
     private int dp[] = new int[1000];
-    public int calcDiceCase(int n) {
+    /**
+     *  메모이제이션을 사용하지 않은 경우
+     *  단점 : 숫자가 커질수록 느려진다.
+     */
+    public int calcDiceCase1(int n) {
+        if (n < 0) return 0;
+        if (n == 0) return 1;
+        return calcDiceCase1(n - 1) + calcDiceCase1(n - 2) + 
+        calcDiceCase1(n - 3) + calcDiceCase1(n - 4) + 
+        calcDiceCase1(n - 5) + calcDiceCase1(n - 6);
+    }
+    /**
+     *  메모이제이션을 사용하는 경우
+     *  장점 : 속도가 빠르다.
+     */
+    public int calcDiceCase2(int n) {
         if (n < 0) return 0;
         if (n == 0) return 1;
         int result = 0;
         for(int i = 1; i<=6; i++){
-            if(i >= 0){
+            if(n - i >= 0){
                 if(dp[n - i] == 0){
-                    dp[n - i] = calcDiceCase(n - i);
+                    dp[n - i] = calcDiceCase2(n - i);
                 }
                 result += dp[n - i];
             }
