try2.java

Java是最优秀的高级编程语言之一,多项式的加法运算,体现了链表数据结构的优势.

/**
 * @(#)Try2.java
 *
 *
 * @author 
 * @version 1.00 2006/11/1
 */

import java.io.*;
import java.lang.*;
public class Try2 {
	public static void main(String[] args){
		String poly="";
    	int length=0;
    	char operator='1';
    	boolean positive=false;
    	int next=0;
    	int start=0;
    	int i=0;
    	System.out.println("Please enter a polynomial(such as 6x^5+2x^2-x+2):");
    	BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
    	try{
    		poly=in.readLine();
    	}catch(IOException e){}
    	int[] coef=new int[poly.length()];
    	int[] exp=new int[poly.length()];
    	for(int j=0;j<poly.length();j++)
    		exp[j]=-1;
		while(next!=-1&&poly.length()>1&&next!=poly.length()-1){
			next=0;
			next=poly.indexOf("x",next);
			if(next!=-1){
			operator=poly.charAt(0);
			if(operator=='+'){
				positive=true;
				start=1;
			}
				else if(operator=='-'){
					positive=false;
					start=1;
				}
					 else if(operator<='9'&&operator>='1')
					 	positive=true;
			if(start==next)
				coef[i]=1;
				else if(start!=next){
					coef[i]=Integer.parseInt(poly.substring(start,next));
					if(!positive)
						coef[i]=-coef[i];
				}
			if(next==poly.length()-1){
				exp[i]=1;
				break;
			}
			next++;
		    if(poly.charAt(next)=='^'){	
		    	start=next+1;
		    	next=start;
		    	operator=poly.charAt(next);
		        for(;operator!='+'&&operator!='-'&&next!=poly.length()-2;)
		        	operator=poly.charAt(++next);
		        exp[i]=Integer.parseInt(poly.substring(start,next));
		    }	
		    	else
		    		exp[i]=1;
			}
			if(next!=-1)
			poly=poly.substring(next);
			start=0;
			i++;
		}
		start=0;
		next=0;
		 if(poly.indexOf("x",0)==-1){
		 	operator=poly.charAt(0);
		 	if(operator=='+')
		 		positive=true;
		 		else positive=false;
		 		start++;
		 		coef[i]=Integer.parseInt(poly.substring(start));
		 		exp[i]=0;
		 		if(!positive)
		 			coef[i]=-coef[i];
		 			
	}
	}
}