Merge pull request #1468 from AlgorithmWithGod/khj20006

[20251121] PGM / LV2 / 삼각 달팽이 / 권혁준

Author: ShinHeeEul

khj20006/202511/21 PGM LV2 삼각 달팽이.md

@@ -0,0 +1,37 @@
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+const int dx[3] = {1,0,-1};
+const int dy[3] = {0,1,-1};
+
+int N;
+int arr[1000][1000]{};
+bool vis[1000][1000]{};
+
+bool oob(int x, int y) {
+    return x<0 || x>=N || y<0 || y>x;
+}
+
+void go(int x, int y, int value, int dir) {
+    if(value > N*(N+1)/2) return;
+    arr[x][y] = value;
+    vis[x][y] = true;
+    int xx = x + dx[dir];
+    int yy = y + dy[dir];
+    if(oob(xx,yy) || vis[xx][yy]) {
+        dir = (dir + 1) % 3;
+        xx = x + dx[dir];
+        yy = y + dy[dir];
+    }
+    go(xx,yy,value+1,dir);
+}
+
+vector<int> solution(int n) {
+    N = n;
+    go(0,0,1,0);
+    vector<int> answer;
+    for(int i=0;i<N;i++) for(int j=0;j<=i;j++) answer.push_back(arr[i][j]);
+    return answer;
+}
+```