Aizu Online Judge 1244 Molecular Formula

■1244 Molecular Formula

構文解析ゲー．

import java.util.*;
import java.lang.*;
import java.math.*;
import java.io.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

// AC
public class Main{

 Scanner sc=new Scanner(System.in);

 HashMap<String, Integer> map;
 String s;
 boolean unknown;

 void run(){
  map=new HashMap<String, Integer>();
  for(;;){
   String s=sc.next();
   if(s.equals("END_OF_FIRST_PART")){
    break;
   }
   int n=sc.nextInt();
   map.put(s, n);
  }
  for(;;){
   s=sc.next();
   if(s.equals("0")){
    break;
   }
   s+='\0';
   unknown=false;
   Result r=molecule(0);
   println(unknown?"UNKNOWN":r.value+"");
   debug(r.p, r.value);
  }
 }

 Result molecule(int p){
  debug("molecule", p);
  Result r=new Result(p, 0);
  for(;;){
   if(s.charAt(r.p)=='\0'||s.charAt(r.p)==')'){
    // end of molecule
    return r;
   }else if(s.charAt(r.p)=='('){
    Result r1=molecule(r.p+1);
    Result r2=number(r1.p+1); // skip '('
    r.value+=r1.value*r2.value;
    r.p=r2.p;
   }else{
    Result r1=atom(r.p);
    Result r2=number(r1.p);
    r.value+=r1.value*r2.value;
    r.p=r2.p;
   }
  }
 }

 Result atom(int p){
  debug("atom", p);
  String atom="";
  if(Character.isUpperCase(s.charAt(p))){
   atom+=s.charAt(p);
   p++;
   if(Character.isLowerCase(s.charAt(p))){
    atom+=s.charAt(p);
    p++;
   }
  }
  debug(atom);
  if(map.containsKey(atom)){
   return new Result(p, map.get(atom));
  }else{
   unknown=true;
   return new Result(p, 0);
  }
 }

 Result number(int p){
  debug("number", p);
  int value=0;
  if(Character.isDigit(s.charAt(p))){
   value=s.charAt(p)-'0';
   p++;
   if(Character.isDigit(s.charAt(p))){
    value=value*10+s.charAt(p)-'0';
    p++;
   }
  }else{
   return new Result(p, 1);
  }
  return new Result(p, value);
 }

 class Result{
  int p, value;

  Result(int p, int value){
   this.p=p;
   this.value=value;
  }
 }

 void debug(Object... os){
  // System.err.println(Arrays.deepToString(os));
 }

 void print(String s){
  System.out.print(s);
 }

 void println(String s){
  System.out.println(s);
 }

 public static void main(String[] args){
  // System.setOut(new PrintStream(new BufferedOutputStream(System.out)));
  new Main().run();
 }
}