From 78912508dd5be89b5552dda43309492386e5fee6 Mon Sep 17 00:00:00 2001
From: Do Hyeon Seok <dohyeondol@gmail.com>
Date: Mon, 14 Jul 2025 01:24:29 +0900
Subject: [PATCH] 2025-07-14

---
 dohyeondol1/README.md                         |  2 +
 .../21-dohyeondol1.cpp"                       | 86 +++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 "dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/21-dohyeondol1.cpp"

diff --git a/dohyeondol1/README.md b/dohyeondol1/README.md
index f44924f..0d4f5bc 100644
--- a/dohyeondol1/README.md
+++ b/dohyeondol1/README.md
@@ -21,3 +21,5 @@
  | 17차시 | 2025.06.26 |  기하학  | [선분 교차 2](https://www.acmicpc.net/problem/17387)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/65|
  | 18차시 | 2025.07.04 |  기하학  | [Water Testing](https://www.acmicpc.net/problem/16057)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/70|
  | 19차시 | 2025.07.09 |  그래프 이론  | [최소 스패닝 트리](https://www.acmicpc.net/problem/1197)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/76|
+ | 20차시 | 2025.07.10 |  문자열  | [접두사](https://www.acmicpc.net/problem/1141)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/78|
+ | 21차시 | 2025.07.14 |  그래프 이론  | [석고 모형 만들기](https://www.acmicpc.net/problem/32031)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/81|
diff --git "a/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/21-dohyeondol1.cpp" "b/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/21-dohyeondol1.cpp"
new file mode 100644
index 0000000..16275b1
--- /dev/null
+++ "b/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/21-dohyeondol1.cpp"	
@@ -0,0 +1,86 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+int height, width;
+int visited[320001];
+char grid[201][201];
+vector<int> graph[320001];
+
+void dfs(int u) {
+    if(visited[u]) 
+        return;
+    visited[u] = true;
+    
+    for(int v : graph[u])
+        dfs(v);
+}
+
+int main() {
+    cin.tie(nullptr)->sync_with_stdio(false);
+
+    cin >> height >> width;
+    for(int i = 0; i < height; ++i) {
+        for(int j = 0; j < width; ++j) {
+            int base = (i * width + j) * 8;
+            char ch;
+            cin >> ch;
+
+            int mask = 0;
+            if(ch == 'H') mask = 1;
+            else if(ch == 'I') mask = 2;
+            else if(ch == 'O') mask = 4;
+
+            for(int k = 0; k < 8; ++k)
+                graph[base + k].push_back(base + (k ^ mask));
+        }
+    }
+
+    for(int i = 0; i < height; ++i) {
+        for(int j = 0; j < width - 1; ++j) {
+            int u = (i * width + j) * 8;
+            int v = (i * width + (j + 1)) * 8;
+
+            graph[u+1].push_back(v);
+            graph[v].push_back(u + 1);
+
+            graph[u+3].push_back(v+2);
+            graph[v+2].push_back(u+3);
+
+            graph[u+5].push_back(v+4);
+            graph[v+4].push_back(u+5);
+
+            graph[u+7].push_back(v+6);
+            graph[v+6].push_back(u+7);
+        }
+    }
+
+    for(int i = 0; i < height - 1; ++i) {
+        for(int j = 0; j < width; ++j) {
+            int u = (i * width + j) * 8;
+            int v = ((i + 1) * width + j) * 8;
+
+            graph[u+2].push_back(v);
+            graph[v].push_back(u+2);
+
+            graph[u+3].push_back(v+1);
+            graph[v+1].push_back(u+3);
+
+            graph[u+6].push_back(v+4);
+            graph[v+4].push_back(u+6);
+
+            graph[u+7].push_back(v+5);
+            graph[v+5].push_back(u+7);
+        }
+    }
+
+    int cnt = 0;
+    for(int i = 0; i < height * width * 8; ++i) {
+        if(visited[i]) continue;
+        dfs(i);
+        cnt++;
+    }
+
+    cout << cnt << '\n';
+    return 0;
+}
\ No newline at end of file