diff --git a/dohyeondol1/README.md b/dohyeondol1/README.md
index 26f1ff5..5821133 100644
--- a/dohyeondol1/README.md
+++ b/dohyeondol1/README.md
@@ -22,3 +22,6 @@
  | 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|
+ | 22차시 | 2025.07.19 |  그리디 알고리즘  | [대회 개최](https://www.acmicpc.net/problem/12915)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/87|
+ | 23차시 | 2025.08.03 |  그래프 이론  | [플로이드](https://www.acmicpc.net/problem/11404)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/93|
\ No newline at end of file
diff --git "a/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/23-dohyeondol1.cpp" "b/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/23-dohyeondol1.cpp"
new file mode 100644
index 0000000..1b82ada
--- /dev/null
+++ "b/dohyeondol1/\352\267\270\353\236\230\355\224\204 \354\235\264\353\241\240/23-dohyeondol1.cpp"	
@@ -0,0 +1,46 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+const int INF = 1e9;
+
+int main() {
+    cin.tie(nullptr)->sync_with_stdio(false);
+    
+    int n, m;
+    cin >> n >> m;
+    vector<vector<int>> dist(n+1, vector<int>(n+1, INF));
+    for(int i = 1; i <= n; i++)
+        dist[i][i] = 0;
+    
+    for(int i = 0; i < m; i++) {
+        int a, b, c;
+        cin >> a >> b >> c;
+        dist[a][b] = min(dist[a][b], c);
+    }
+    
+    for(int k = 1; k <= n; k++) {
+        for(int i = 1; i <= n; i++) {
+            for(int j = 1; j <= n; j++) {
+                if(dist[i][k] != INF && dist[k][j] != INF) {
+                    dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
+                }
+            }
+        }
+    }
+    
+    for(int i = 1; i <= n; i++) {
+        for(int j = 1; j <= n; j++) {
+            if(dist[i][j] == INF) {
+                cout << 0 << " ";
+            } 
+            else {
+                cout << dist[i][j] << " ";
+            }
+        }
+        cout << '\n';
+    }
+    
+    return 0;
+}
\ No newline at end of file