From fe7403f17cf76570526b98d254bec7609a070b07 Mon Sep 17 00:00:00 2001
From: songyc macbook <gitea@gitea>
Date: Wed, 7 Jan 2026 23:12:16 +0900
Subject: [PATCH] baekjoon 20260107

---
 code_study/Baekjoon/c/13172.c      | 33 ++++++++++++++++++++++++++++
 code_study/Baekjoon/c/24883.c      |  8 +++++++
 code_study/Baekjoon/python/1865.py | 35 ++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 code_study/Baekjoon/c/13172.c
 create mode 100644 code_study/Baekjoon/c/24883.c
 create mode 100644 code_study/Baekjoon/python/1865.py

diff --git a/code_study/Baekjoon/c/13172.c b/code_study/Baekjoon/c/13172.c
new file mode 100644
index 0000000..94e4956
--- /dev/null
+++ b/code_study/Baekjoon/c/13172.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#define MOD 1000000007
+
+long long power(long long a, int n);
+
+int main() {
+    int M;
+    scanf("%d",&M);
+
+    long long ans = 0;
+    while(M--) {
+        long long N, S;
+        scanf("%lld %lld",&N, &S);
+        ans += (S*power(N, MOD-2))%MOD;
+    }
+
+    printf("%lld\n", ans%MOD);
+
+    return 0;
+}
+
+long long power(long long a, int n) {
+    if(n==0) return 1;
+    if(n==1) return a%MOD;
+
+    long long temp = power(a, n/2);
+    long long result = temp*temp%MOD;
+
+    if(n%2) result = result*a%MOD;
+
+    return result;
+}
\ No newline at end of file
diff --git a/code_study/Baekjoon/c/24883.c b/code_study/Baekjoon/c/24883.c
new file mode 100644
index 0000000..2e7566f
--- /dev/null
+++ b/code_study/Baekjoon/c/24883.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main() {
+    char n;
+    scanf("%c",&n);
+    printf("Naver %s\n", n=='N' || n=='n' ? "D2" : "Whale");
+    return 0;
+}
\ No newline at end of file
diff --git a/code_study/Baekjoon/python/1865.py b/code_study/Baekjoon/python/1865.py
new file mode 100644
index 0000000..d1a2103
--- /dev/null
+++ b/code_study/Baekjoon/python/1865.py
@@ -0,0 +1,35 @@
+import sys
+
+input = sys.stdin.readline
+
+def bellman_ford(edges, N) :
+    dist = [0]*(N+1)
+    
+    for n in range(N) :
+        for s,e,t in edges :
+            if dist[e] > dist[s] + t :
+                dist[e] = dist[s] + t
+
+                if n == N-1:
+                    return True
+                
+    return False
+
+ans = []
+
+for _ in range(int(input())) :
+    N, M, W = map(int, input().split())
+    edges = []
+    
+    for _ in range(M) :
+        S, E, T = map(int, input().split())
+        edges.append((S,E,T))
+        edges.append((E,S,T))
+    
+    for _ in range(W) :
+        S, E, T = map(int, input().split())
+        edges.append((S,E,-T))
+    
+    ans.append("YES" if bellman_ford(edges, N) else "NO")
+
+print("\n".join(ans))
\ No newline at end of file