[20251108] PGM / LV2 / 삼각 달팽이 / 강신지

ksinji/202511/8 PGM 삼각 달팽이.md

@@ -0,0 +1,44 @@
+```java
+import java.util.*;
+
+class Solution {
+    public int[] solution(int n) {
+        int total = n * (n + 1) / 2;
+        int[][] tri = new int[n][n];
+
+        int num = 1;
+        int r = -1;
+        int c = 0;
+        int len = n;
+
+        while (len > 0) {
+            for (int i = 0; i < len; i++) {
+                tri[++r][c] = num++;
+            }
+            len--;
+            if (len == 0) break;
+
+            for (int i = 0; i < len; i++) {
+                tri[r][++c] = num++;
+            }
+            len--;
+            if (len == 0) break;
+
+            for (int i = 0; i < len; i++) {
+                tri[--r][--c] = num++;
+            }
+            len--;
+        }
+
+        int[] answer = new int[total];
+        int idx = 0;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j <= i; j++) {
+                answer[idx++] = tri[i][j];
+            }
+        }
+        return answer;
+    }
+}
+
+```