HDU5898数位DP

求区间[L，R]，满足：

连续奇数个数为偶数  或者 

连续偶数个数为奇数 

的个数。

注意前缀为0的特殊情况

import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.io.PrintWriter;import java.math.BigInteger;import java.util.StringTokenizer;public class Main {public static void main(String[] args) {new P1007().main();}}class P1007 {final int Max_N = 20;final int ODD = 1;final int EVEN = 0;final BigInteger ten = BigInteger.valueOf(10);long[][][] dp = new long[Max_N][2][Max_N];int[] bit = new int[Max_N];boolean isEven(int x) {return (x & 1) == 0;}boolean isOdd(int x) {return (x & 1) == 1;}long DP(int pos, int pre, int bitSum, boolean isend) {if (pos == -1) {if (pre == EVEN)return isOdd(bitSum) ? 1L : 0L;elsereturn isEven(bitSum) ? 1L : 0L;}if (pre != -1 && !isend && dp[pos][pre][bitSum] != -1)return dp[pos][pre][bitSum];int d = isend ? bit[pos] : 9;long ans = 0;for (int i = 0; i <= d; i++) {if (pre == -1) {if (i == 0)ans += DP(pos - 1, -1, bitSum, isend && (i == d));else if (isEven(i))ans += DP(pos - 1, EVEN, bitSum + 1, isend && (i == d));elseans += DP(pos - 1, ODD, bitSum + 1, isend && (i == d));} else if (pre == EVEN) {if (isEven(i))ans += DP(pos - 1, EVEN, bitSum + 1, isend && (i == d));else {if (isEven(bitSum)) {ans += 0;} elseans += DP(pos - 1, ODD, 1, isend && (i == d));}} else if (pre == ODD) {if (isOdd(i))ans += DP(pos - 1, ODD, bitSum + 1, isend && (i == d));else {if (isOdd(bitSum)) {ans += 0;} elseans += DP(pos - 1, EVEN, 1, isend && (i == d));}}}if (pre != -1 && !isend)dp[pos][pre][bitSum] = ans;return ans;}long Ans(BigInteger x) {int Len = 0;while (x.compareTo(BigInteger.ZERO) > 0) {bit[Len++] = x.mod(ten).intValue();x = x.divide(ten);}return DP(Len - 1, -1, 0, true);}InputReader in = new InputReader(System.in);PrintWriter out = new PrintWriter(System.out);void main() {for (int i = 0; i < Max_N; i++) {for (int j = 0; j < 2; j++) {for (int k = 0; k < Max_N; k++) {dp[i][j][k] = -1;}}}BigInteger l, r;int t = in.nextInt();for (int ca = 1; ca <= t; ca++) {out.print("Case #" + ca + ": ");l = in.nextBigInteger();r = in.nextBigInteger();long sr = Ans(r);long sl = Ans(l.subtract(BigInteger.ONE));out.println(sr - sl);}out.flush();}}class InputReader {public BufferedReader reader;public StringTokenizer tokenizer;public InputReader(InputStream stream) {reader = new BufferedReader(new InputStreamReader(stream), 32768);tokenizer = new StringTokenizer("");}private void eat(String s) {tokenizer = new StringTokenizer(s);}public String nextLine() {try {return reader.readLine();} catch (Exception e) {return null;}}public boolean hasNext() {while (!tokenizer.hasMoreTokens()) {String s = nextLine();if (s == null)return false;eat(s);}return true;}public String next() {hasNext();return tokenizer.nextToken();}public int nextInt() {return Integer.parseInt(next());}public long nextLong() {return Long.parseLong(next());}public double nextDouble() {return Double.parseDouble(next());}public BigInteger nextBigInteger() {return new BigInteger(next());}}