20251109 baekjoon

code_study/Baekjoon/swift/1647.swift

@@ -0,0 +1,80 @@
+struct Union {
+    var parent: [Int]
+    
+    init(_ N: Int) {
+        self.parent = Array(0...N)
+    }
+    
+    mutating func findParent(_ x: Int) -> Int {
+        if x != parent[x] {
+            parent[x] = findParent(parent[x])
+        }
+        return parent[x]
+    }
+    
+    mutating func union(_ x: Int, _ y: Int) {
+        let parentX = findParent(x)
+        let parentY = findParent(y)
+        
+        if parentX < parentY {
+            parent[parentY] = parentX
+        }
+        else {
+            parent[parentX] = parentY
+        }
+    }
+    
+    mutating func isSameParent(_ a: Int, _ b: Int) -> Bool {
+        return findParent(a) == findParent(b)
+    }
+}
+
+if let input1 = readLine(),
+   let NM = input1.split(separator: " ").compactMap({Int($0)}) as? [Int],
+   let N = NM.first, let M = NM.last
+{
+    if N==2 {
+        print(0)
+    }
+    else {
+        var edges: [(u:Int, v: Int, w: Int)] = []
+        for _ in 0..<M {
+            guard let input2 = readLine(),
+                  let edge = input2.split(separator: " ").compactMap({Int($0)}) as? [Int],
+                  edge.count == 3
+            else {continue}
+            
+            let u = min(edge[0], edge[1])
+            let v = max(edge[0], edge[1])
+            let w = edge[2]
+            
+            edges.append((u: u, v: v, w: w))
+        }
+        
+        edges.sort {
+            if $0.w == $1.w {
+                return $0.u < $1.u
+            }
+            return $0.w < $1.w
+        }
+        
+        var root = Union(N)
+        var edgeCount = 0
+        var totalWeight = 0
+        
+        for e in edges {
+            let (u, v, w) = e
+            
+            if !root.isSameParent(u, v) {
+                root.union(u, v)
+                totalWeight += w
+                edgeCount += 1
+                
+                if(edgeCount == N-2) {
+                    print(totalWeight)
+                    break
+                }
+            }
+        }
+    }
+}