From 289d125a19903f86803618cde14025b44185a67e Mon Sep 17 00:00:00 2001
From: songyc macbook <gitea@gitea>
Date: Wed, 10 Dec 2025 22:10:23 +0900
Subject: [PATCH] baekjoon 20251210

---
 code_study/Baekjoon/c/10844.c        | 39 ++++++++++++++++++++++++++++
 code_study/Baekjoon/python/15681.py  | 26 +++++++++++++++++++
 code_study/Baekjoon/swift/1806.swift | 34 ++++++++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 code_study/Baekjoon/c/10844.c
 create mode 100644 code_study/Baekjoon/python/15681.py
 create mode 100644 code_study/Baekjoon/swift/1806.swift

diff --git a/code_study/Baekjoon/c/10844.c b/code_study/Baekjoon/c/10844.c
new file mode 100644
index 0000000..4785a56
--- /dev/null
+++ b/code_study/Baekjoon/c/10844.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+
+#define MOD 1000000000
+long long dp[101][10];
+
+int main() {
+    for (int i=1; i<10; i++) dp[1][i] = 1;
+    
+    int N;
+    scanf("%d",&N);
+
+    for (int n=1; n<N; n++) {
+        for (int num=0; num<10; num++) {
+
+            if (dp[n][num] == 0) continue;
+
+            int next_num = num - 1;
+            if (0<=next_num && next_num <=9) {
+                dp[n+1][next_num] += dp[n][num];
+                dp[n+1][next_num] %= MOD;
+            }
+
+            next_num = num + 1;
+            if (0<=next_num && next_num <=9) {
+                dp[n+1][next_num] += dp[n][num];
+                dp[n+1][next_num] %= MOD;
+            }
+        }
+    }
+
+    long long result = 0;
+    for(int i=0; i<10; i++) {
+        result += dp[N][i];
+        result %= MOD;
+    }
+    printf("%lld\n",result);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/code_study/Baekjoon/python/15681.py b/code_study/Baekjoon/python/15681.py
new file mode 100644
index 0000000..e22a052
--- /dev/null
+++ b/code_study/Baekjoon/python/15681.py
@@ -0,0 +1,26 @@
+import sys
+sys.setrecursionlimit(10**6)
+input = sys.stdin.readline
+
+N, R, Q = map(int, input().split())
+
+edges = [[] for _ in range(N+1)]
+
+for _ in range(N-1) :
+    u, v = map(int, input().split())
+    edges[u].append(v)
+    edges[v].append(u)
+
+dp = [0]*(N+1)
+
+def dfs(current, parent) :
+    dp[current] = 1
+    
+    for next in edges[current] :
+        if next != parent :
+            dfs(next, current)
+            dp[current] += dp[next]
+
+dfs(R, 0)
+
+print("\n".join(map(str, [dp[int(input())] for _ in range(Q)])))
\ No newline at end of file
diff --git a/code_study/Baekjoon/swift/1806.swift b/code_study/Baekjoon/swift/1806.swift
new file mode 100644
index 0000000..121b168
--- /dev/null
+++ b/code_study/Baekjoon/swift/1806.swift
@@ -0,0 +1,34 @@
+func solve() {
+    guard let input1 = readLine(),
+          let NS = input1.split(separator: " ").compactMap({Int($0)}) as? [Int],
+          let N = NS.first, let S = NS.last
+    else { return }
+    
+    guard let input2 = readLine(),
+          let seq = input2.split(separator: " ").compactMap({Int($0)}) as? [Int]
+    else { return }
+    
+    var minLength = Int.max
+    var L = 0, R = 0
+    var acc = 0
+    
+    while true {
+        if acc >= S {
+            minLength = min(minLength, R-L)
+            acc -= seq[L]
+            L += 1
+        }
+        else if R == N {
+            break
+        }
+        else {
+            acc += seq[R]
+            R += 1
+        }
+    }
+    
+    let result = minLength == Int.max ? 0 : minLength
+    print(result)
+}
+
+solve()
\ No newline at end of file