modify code

Author: algorithmzuo

src/class166/Code01_SegmentTreeDivideAndConquer1.java

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+package class166;
+
+// 线段树分治模版题，java版
+// 测试链接 : https://www.luogu.com.cn/problem/P5787
+// 提交以下的code，提交时请把类名改成"Main"，可以通过所有测试用例
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+import java.io.StreamTokenizer;
+
+public class Code01_SegmentTreeDivideAndConquer1 {
+
+	public static int MAXN = 100001;
+	public static int MAXM = 200001;
+	public static int MAXT = 3000001;
+	public static int n, m, k;
+	public static int[][] edge = new int[MAXM][2];
+
+	public static int[] father = new int[MAXN << 1];
+	public static int[] siz = new int[MAXN << 1];
+	public static int[][] rollback = new int[MAXN << 1][2];
+	public static int opsize;
+
+	public static int[] head = new int[MAXT];
+	public static int[] next = new int[MAXT];
+	public static int[] to = new int[MAXT];
+	public static int cnt = 0;
+
+	public static boolean[] ans = new boolean[MAXN];
+
+	public static void addQuery(int u, int v) {
+		next[++cnt] = head[u];
+		to[cnt] = v;
+		head[u] = cnt;
+	}
+
+	public static int find(int i) {
+		while (i != father[i]) {
+			i = father[i];
+		}
+		return i;
+	}
+
+	public static void union(int x, int y) {
+		int fx = find(x);
+		int fy = find(y);
+		if (siz[fx] < siz[fy]) {
+			int tmp = fx;
+			fx = fy;
+			fy = tmp;
+		}
+		father[fy] = fx;
+		siz[fx] += siz[fy];
+		rollback[++opsize][0] = fx;
+		rollback[opsize][1] = fy;
+	}
+
+	public static void undo() {
+		int fx = rollback[opsize][0];
+		int fy = rollback[opsize--][1];
+		father[fy] = fy;
+		siz[fx] -= siz[fy];
+	}
+
+	public static void add(int jobl, int jobr, int jobv, int l, int r, int i) {
+		if (l > jobr || r < jobl) {
+			return;
+		}
+		if (jobl <= l && r <= jobr) {
+			addQuery(i, jobv);
+		} else {
+			int mid = (l + r) / 2;
+			add(jobl, jobr, jobv, l, mid, i << 1);
+			add(jobl, jobr, jobv, mid + 1, r, i << 1 | 1);
+		}
+	}
+
+	public static void dfs(int l, int r, int i) {
+		boolean check = true;
+		int x, y, fx, fy, unionCnt = 0;
+		for (int e = head[i]; e > 0; e = next[e]) {
+			x = edge[to[e]][0];
+			y = edge[to[e]][1];
+			fx = find(x);
+			fy = find(y);
+			if (fx == fy) {
+				check = false;
+				break;
+			} else {
+				union(x, y + n);
+				union(y, x + n);
+				unionCnt += 2;
+			}
+		}
+		if (check) {
+			if (l == r) {
+				ans[l] = true;
+			} else {
+				int mid = (l + r) / 2;
+				dfs(l, mid, i << 1);
+				dfs(mid + 1, r, i << 1 | 1);
+			}
+		} else {
+			for (int k = l; k <= r; k++) {
+				ans[k] = false;
+			}
+		}
+		for (int k = 1; k <= unionCnt; k++) {
+			undo();
+		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StreamTokenizer in = new StreamTokenizer(br);
+		PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
+		in.nextToken();
+		n = (int) in.nval;
+		in.nextToken();
+		m = (int) in.nval;
+		in.nextToken();
+		k = (int) in.nval;
+		for (int i = 1, l, r; i <= m; i++) {
+			in.nextToken();
+			edge[i][0] = (int) in.nval;
+			in.nextToken();
+			edge[i][1] = (int) in.nval;
+			in.nextToken();
+			l = (int) in.nval + 1;
+			in.nextToken();
+			r = (int) in.nval;
+			add(l, r, i, 1, k, 1);
+		}
+		for (int i = 1; i <= n * 2; i++) {
+			father[i] = i;
+			siz[i] = 1;
+		}
+		dfs(1, k, 1);
+		for (int i = 1; i <= k; i++) {
+			if (ans[i]) {
+				out.println("Yes");
+			} else {
+				out.println("No");
+			}
+		}
+		out.flush();
+		out.close();
+		br.close();
+	}
+
+}