[20251010] PGM / Lv3 / 산 모양 타일링 / 이종환

Author: 0224LJH

0224LJH/202510/10 PGM 산 모양 타일링.md

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+```java
+import java.io.*;
+import java.util.*;
+
+class Solution {
+    static int size;
+    static boolean[] hasTop;
+    static int[][] dp;
+    
+    static final int EMPTY = 0;
+    static final int LEFT = 1;
+    static final int TOP = 2;
+    static final int RIGHT = 3;
+    static final int REMAINDER = 10007;
+    
+    public int solution(int n, int[] tops) {
+        size = n;
+        hasTop = new boolean[n];
+        dp = new int[size][4];
+
+        for (int i = 0; i < n; i++) hasTop[i] = tops[i] == 1;
+        
+        process();
+        
+        
+        int answer = dp[size-1][EMPTY] + dp[size-1][LEFT] +  dp[size-1][TOP] +  dp[size-1][RIGHT] ;
+        answer %= REMAINDER;
+        return answer;
+    }
+    
+    private void process(){
+        // i번칸의 경우의 수
+        // dp[i][아무것도 안함]=  dp[i-1][모든 경우]
+        // dp[i][왼쪽으로 뻗음] = dp[i-1][왼쪽으로 뻗음] + dp[i-1][위로뻗음] + dp[i-1][아무것도 안함]
+        // dp[i][위로 뻗음] = (top이 있음)? dp[i-1][모든 경우]: 0;
+        // dp[i][오른쪽으로 뻗음] = dp[i-1]모든 경우
+        
+        dp[0][EMPTY] = 1;
+        dp[0][LEFT] = 1;
+        dp[0][RIGHT] = 1;
+        if (hasTop[0]) dp[0][TOP] = 1;
+        
+        for (int i = 1; i < size; i++){
+            int sum = dp[i-1][EMPTY] + dp[i-1][TOP] + dp[i-1][LEFT] + dp[i-1][RIGHT];
+            dp[i][EMPTY] = sum%REMAINDER;
+            dp[i][LEFT] = (sum-dp[i-1][RIGHT])%REMAINDER;
+            dp[i][RIGHT] = sum%REMAINDER;
+            if(hasTop[i]) dp[i][TOP] = sum%REMAINDER;
+        }
+    }
+}
+```