HDU4722数位DP

If we sum up every digit of a number and the result can be exactly divided by 10, we say this number is a good number.

You are required to count the number of good numbers in the range from A to B, inclusive.

import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.io.PrintWriter;import java.math.BigInteger;import java.util.Arrays;import java.util.StringTokenizer;public class Main {public static void main(String[] args) {new Task().solve(); }}class Task{InputReader in = new InputReader(System.in) ;PrintWriter out = new PrintWriter(System.out) ;void solve(){int t = in.nextInt() ;for(int cas = 1 ; cas <= t ; cas++){long l = in.nextLong() ;long r = in.nextLong() ;out.print("Case #" + cas + ": ");out.println(work(r) - work(l-1)) ;}out.flush();}    int[] bit = new int[20] ;    long[][] dp = new long[20][10] ;    {    for(int i = 0 ; i < 20 ; i++) Arrays.fill(dp[i] , -1) ;    }    long dfs(int pos , int sum , boolean isEnd){    if(pos < 0){    return sum == 0 ? 1 : 0 ;    }    if(!isEnd && dp[pos][sum] != -1) return dp[pos][sum] ;    int d = isEnd ?  bit[pos] : 9 ;    long result = 0 ;    for(int i = 0 ; i <= d ; i++){    result += dfs(pos-1 , (sum+i)%10 , isEnd&&i==d) ;    }    if(!isEnd) dp[pos][sum] = result ;    return result ;}long work(long x){if(x < 0) return 0 ;int len = 0 ; while(x > 0){bit[len++] = (int) (x % 10) ;x /= 10 ; }return dfs(len-1, 0, true) ;}} 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());      }    }