[java] SWEA 1248

seoul_15_suminkim/SWEA/Solution_d5_1248.java

@@ -0,0 +1,116 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+public class Solution_d5_1248 {
+
+ static int v;
+ static List<Integer>[] adj;
+ static int[][] sTable;
+ static int[] depth;
+ static int[] subTree;
+ static int k;
+
+ public static void main(String[] args) throws IOException {
+ BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+ int tc = Integer.parseInt(br.readLine());
+ StringBuilder sb = new StringBuilder();
+ for (int t = 1; t <= tc; t++) {
+ StringTokenizer st = new StringTokenizer(br.readLine());
+ v = Integer.parseInt(st.nextToken());
+ k = 32 - Integer.numberOfLeadingZeros(v);
+ int e = Integer.parseInt(st.nextToken());
+ int v1 = Integer.parseInt(st.nextToken());
+ int v2 = Integer.parseInt(st.nextToken());
+ setGraph(br.readLine(), e);
+ setParent();
+ setSTable();
+ setSubTree();
+ int lca = lca(v1, v2);
+ sb.append("#" + t + " " + lca + " " + subTree[lca] + "\n");
+ }
+ System.out.println(sb);
+ }
+
+ private static void setGraph(String readLine, int e) {
+ StringTokenizer st = new StringTokenizer(readLine);
+ adj = new List[v + 1];
+ for (int i = 1; i <= v; i++) {
+ adj[i] = new LinkedList<>();
+ }
+ for (int i = 0; i < e; i++) {
+ int v1 = Integer.parseInt(st.nextToken());
+ int v2 = Integer.parseInt(st.nextToken());
+ adj[v1].add(v2);
+ adj[v2].add(v1);
+ }
+ }
+
+ private static void setParent() {
+ sTable = new int[v + 1][k];
+ depth = new int[v + 1];
+ sTable[1][0] = 1;
+ setParent(1);
+ }
+
+ private static void setParent(int root) {
+ for (int child : adj[root]) {
+ if (sTable[child][0] > 0) continue;
+ sTable[child][0] = root;
+ depth[child] = depth[root] + 1;
+ setParent(child);
+ }
+ }
+
+ private static void setSTable() {
+ for (int d = 1; d < k; d++) {
+ for (int i = 1; i <= v; i++) {
+ sTable[i][d] = sTable[sTable[i][d - 1]][d - 1];
+ }
+ }
+ }
+
+ private static void setSubTree() {
+ subTree = new int[v + 1];
+ setSubTree(1);
+ }
+
+ private static int setSubTree(int root) {
+ if (subTree[root] != 0) return subTree[root];
+ subTree[root] = 1;
+ for (int child : adj[root]) {
+ if (sTable[child][0] != root) continue;
+ subTree[root] += setSubTree(child);
+ }
+ return subTree[root];
+ }
+
+ private static int lca(int v1, int v2) {
+ // v1이 더 깊은쪽이 되도록 변환
+ if (depth[v1] < depth[v2]) {
+ int temp = v1;
+ v1 = v2;
+ v2 = temp;
+ }
+ // v1, v2 depth 맞추기
+ for (int i = k - 1; i >= 0; i--) {
+ if (depth[v1] - depth[v2] >= (1 << i)) {
+ v1 = sTable[v1][i];
+ }
+ }
+ // 같아지면 같아진값 반환
+ if (v1 == v2) return v1;
+ // 공통 조상 찾기 : 가장 위쪽의 서로 다른 조상
+ for (int i = k - 1; i >= 0; i--) {
+ if (sTable[v1][i] != sTable[v2][i]) {
+ v1 = sTable[v1][i];
+ v2 = sTable[v2][i];
+ }
+ }
+ return sTable[v1][0];
+ }
+
+}