[20260222] BOJ / G3 / 불우이웃돕기 / 이준희

Author: JHLEE325

JHLEE325/202602/22 BOJ G3 불우이웃돕기.md

@@ -0,0 +1,88 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int[] parent;
+
+    static class Edge implements Comparable<Edge> {
+        int u, v, w;
+        Edge(int u, int v, int w) {
+            this.u = u;
+            this.v = v;
+            this.w = w;
+        }
+        @Override
+        public int compareTo(Edge o) {
+            return this.w - o.w;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+        int N = Integer.parseInt(br.readLine());
+
+        List<Edge> edges = new ArrayList<>();
+        long totalLength = 0;
+
+        for (int i = 0; i < N; i++) {
+            String line = br.readLine();
+            for (int j = 0; j < N; j++) {
+                char c = line.charAt(j);
+                int len = charToInt(c);
+
+                if (len > 0) {
+                    totalLength += len;
+                    if (i != j) {
+                        edges.add(new Edge(i, j, len));
+                    }
+                }
+            }
+        }
+
+        Collections.sort(edges);
+
+        parent = new int[N];
+        for (int i = 0; i < N; i++) parent[i] = i;
+
+        int useEdgeCount = 0;
+        long mstSum = 0;
+
+        for (Edge edge : edges) {
+            if (union(edge.u, edge.v)) {
+                mstSum += edge.w;
+                useEdgeCount++;
+            }
+        }
+
+        if (useEdgeCount == N - 1) {
+            System.out.println(totalLength - mstSum);
+        } else {
+            System.out.println(-1);
+        }
+    }
+
+    static int charToInt(char c) {
+        if (c >= 'a' && c <= 'z') return c - 'a' + 1;
+        if (c >= 'A' && c <= 'Z') return c - 'A' + 27;
+        return 0;
+    }
+
+    static int find(int x) {
+        if (parent[x] == x) return x;
+        return parent[x] = find(parent[x]);
+    }
+
+    static boolean union(int x, int y) {
+        int rootX = find(x);
+        int rootY = find(y);
+        if (rootX != rootY) {
+            parent[rootX] = rootY;
+            return true;
+        }
+        return false;
+    }
+}
+```