baekjoon 20251228

code_study/Baekjoon/python/5565.py

@@ -0,0 +1 @@
+print(int(input()) - sum([int(input()) for _ in range(9)]))

code_study/Baekjoon/swift/17103.swift

@@ -0,0 +1,41 @@
+import Foundation
+
+let MAX_NUM: Int = 1000000
+let SQRT_MAX = Int(sqrt(Double(MAX_NUM)))
+
+var isPrime: [Bool] = Array(repeating: true, count: MAX_NUM+1)
+(isPrime[0], isPrime[1]) = (false, false)
+
+for n in 2...SQRT_MAX {
+    if isPrime[n] {
+        for i in stride(from: n*n, through: MAX_NUM, by: n) {
+            isPrime[i] = false
+        }
+    }
+}
+
+func pairCount(_ num: Int) -> Int {
+    var ans: Int = 0
+    
+    for n in 2...num/2 {
+        if isPrime[n] && isPrime[num-n] {
+            ans += 1
+        }
+    }
+    
+    return ans
+}
+
+func solve() -> [String] {
+    var result: [String] = []
+    guard let T = Int(readLine() ?? "") else { return []}
+    
+    for _ in 0..<T {
+        guard let N = Int(readLine() ?? "") else { break }
+        result.append(String(pairCount(N)))
+    }
+    
+    return result
+}
+
+print(solve().joined(separator: "\n"))

code_study/Baekjoon/swift/2623.swift

@@ -0,0 +1,51 @@
+func solve() {
+    guard let input1 = readLine() else { return }
+    var NM = input1.split(separator : " ").compactMap{Int($0)}
+    let (N, M) = (NM[0], NM[1])
+    
+    var graph: [[Int]] = Array(repeating: [], count: N+1)
+    var indegree: [Int] = Array(repeating: 0, count: N+1)
+    
+    for _ in 1...M {
+        guard let input2 = readLine() else { break }
+        let seq: [Int] = input2.split(separator: " ").compactMap{Int($0)}
+        
+        for i in 1..<seq[0] {
+            let (u, v) = (seq[i], seq[i+1])
+            graph[u].append(v)
+            indegree[v] += 1
+        }
+    }
+    
+    var qu: [Int] = []
+    var idx: Int = 0
+    var result: [String] = []
+    
+    for i in 1...N {
+        if indegree[i] == 0 {
+            qu.append(i)
+        }
+    }
+    
+    while idx < qu.count {
+        let now: Int = qu[idx]
+        idx += 1
+        result.append(String(now))
+        
+        for nxt in graph[now] {
+            indegree[nxt] -= 1
+            if indegree[nxt] == 0 {
+                qu.append(nxt)
+            }
+        }
+    }
+    
+    if result.count != N {
+        print(0)
+        return
+    }
+    
+    print(result.joined(separator: "\n"))
+}
+
+solve()