Codeforces Round #368 Div2 D. Persistent Bookcase
問題
N 行 M 列のビットがあり、最初は全て 0 である。以下の 4 種類のクエリが来るので、各クエリの操作後のビットの合計を出力せよ。
- i 行 j 列のビットが0であれば1にする。1ならば何もしない。
- i 行 j 列のビットが1であれば0にする。0ならば何もしない。
- i 行 のビットを全て反転させる。
- k 回目のクエリの直後の状態へ戻す。
解法
各操作の順番はツリーとして表現することができる。各操作は十分軽いのでDFSしていけば良い。
コード
import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintWriter; import java.util.ArrayList; import java.util.NoSuchElementException; /* _ooOoo_ o8888888o 88" . "88 (| -_- |) O\ = /O ____/`---'\____ .' \\| |// `. / \\||| : |||// \ / _||||| -:- |||||- \ | | \\\ - /// | | | \_| ''\---/'' | | \ .-\__ `-` ___/-. / ___`. .' /--.--\ `. . __ ."" '< `.___\_<|>_/___.' >'"". | | : `- \`.;`\ _ /`;.`/ - ` : | | \ \ `-. \_ __\ /__ _/ .-` / / ======`-.____`-.___\_____/___.-`____.-'====== `=---=' ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ pass System Test! */ public class D { private static class Task { ArrayList<Integer>[] graph; int[][] queries; boolean[][] shelf; boolean[] inverted; int[] ans; int[] books; int N, M; void dfs(int v) { for (int u : graph[v]) { int type = queries[u][0]; if (type == 1) { int i = queries[u][1]; int j = queries[u][2]; if (!inverted[i]) { if (shelf[i][j]) { ans[u] = ans[v]; dfs(u); } else { shelf[i][j] = true; ans[u] = ans[v] + 1; books[i]++; dfs(u); shelf[i][j] = false; books[i]--; } } else { if (!shelf[i][j]) { ans[u] = ans[v]; dfs(u); } else { shelf[i][j] = false; ans[u] = ans[v] + 1; books[i]++; dfs(u); shelf[i][j] = true; books[i]--; } } } if (type == 2) { int i = queries[u][1]; int j = queries[u][2]; if (!inverted[i]) { if (!shelf[i][j]) { ans[u] = ans[v]; dfs(u); } else { shelf[i][j] = false; ans[u] = ans[v] - 1; books[i]--; dfs(u); shelf[i][j] = true; books[i]++; } } else { if (shelf[i][j]) { ans[u] = ans[v]; dfs(u); } else { shelf[i][j] = true; ans[u] = ans[v] - 1; books[i]--; dfs(u); shelf[i][j] = false; books[i]++; } } } if (type == 3) { int i = queries[u][1]; ans[u] = ans[v] - books[i]; books[i] = M - books[i]; ans[u] += books[i]; inverted[i] = !inverted[i]; dfs(u); inverted[i] = !inverted[i]; books[i] = M - books[i]; } if (type == 4) dfs(u); } } void solve(FastScanner in, PrintWriter out) { N = in.nextInt(); M = in.nextInt(); int Q = in.nextInt(); queries = new int[Q + 1][]; for (int i = 1; i <= Q; i++) { int type = in.nextInt(); if (type <= 2) { queries[i] = new int[]{type, in.nextInt() - 1, in.nextInt() - 1}; } else if (type == 3) { queries[i] = new int[]{type, in.nextInt() - 1}; } else { queries[i] = new int[]{type, in.nextInt()}; } } graph = new ArrayList[Q + 1]; for (int i = 0; i < Q + 1; i++) { graph[i] = new ArrayList<>(); } int cur = 0; int[] after = new int[Q + 1]; for (int i = 1; i <= Q; i++) { int type = queries[i][0]; if (type != 4) { graph[cur].add(i); cur = i; } else { int k = queries[i][1]; cur = after[k]; } after[i] = cur; } shelf = new boolean[N][M]; inverted = new boolean[N]; ans = new int[Q + 1]; books = new int[N]; dfs(0); for (int i = 1; i <= Q; i++) { if (queries[i][0] == 4) { int k = queries[i][1]; ans[i] = ans[k]; } } for (int i = 1; i <= Q; i++) { out.println(ans[i]); } } } /** * ここから下はテンプレートです。 */ public static void main(String[] args) { OutputStream outputStream = System.out; FastScanner in = new FastScanner(); PrintWriter out = new PrintWriter(outputStream); Task solver = new Task(); solver.solve(in, out); out.close(); } private static class FastScanner { private final InputStream in = System.in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int bufferLength = 0; private boolean hasNextByte() { if (ptr < bufferLength) { return true; } else { ptr = 0; try { bufferLength = in.read(buffer); } catch (IOException e) { e.printStackTrace(); } if (bufferLength <= 0) { return false; } } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1; } private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126; } private void skipUnprintable() { while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; } boolean hasNext() { skipUnprintable(); return hasNextByte(); } public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while (isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) { throw new NumberFormatException(); } while (true) { if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; } else if (b == -1 || !isPrintableChar(b)) { return minus ? -n : n; } else { throw new NumberFormatException(); } b = readByte(); } } double nextDouble() { return Double.parseDouble(next()); } double[] nextDoubleArray(int n) { double[] array = new double[n]; for (int i = 0; i < n; i++) { array[i] = nextDouble(); } return array; } double[][] nextDoubleMap(int n, int m) { double[][] map = new double[n][]; for (int i = 0; i < n; i++) { map[i] = nextDoubleArray(m); } return map; } public int nextInt() { return (int) nextLong(); } public int[] nextIntArray(int n) { int[] array = new int[n]; for (int i = 0; i < n; i++) array[i] = nextInt(); return array; } public long[] nextLongArray(int n) { long[] array = new long[n]; for (int i = 0; i < n; i++) array[i] = nextLong(); return array; } public String[] nextStringArray(int n) { String[] array = new String[n]; for (int i = 0; i < n; i++) array[i] = next(); return array; } public char[][] nextCharMap(int n) { char[][] array = new char[n][]; for (int i = 0; i < n; i++) array[i] = next().toCharArray(); return array; } } }