newclass.java

将前缀表达式转为中缀表达式

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package pro;

/**
 *
 * @author Administrator
 */
public class NewClass {
    static char[] a;
    static double[] c;
    static int i,j;
    static char[] b;
    static String[] zh;
    static J_Tree root;
    public static J_Tree JReadExpre(String o){
        int n,i1;
        J_Tree p=null,q=null;
        char[] a1;
        n=o.length();
        a1=new char[n];
        a1[0]=o.charAt(0);
        p=new J_Tree(a1[0]);
        q=p;root=p;
        for(i1=1;i1<n;i1++){
            a1[i1]=o.charAt(i1);
            if(a1[i1]=='+'||a1[i1]=='-'||a1[i1]=='*'||a1[i1]=='/'||a1[i1]=='^'){
                q=new J_Tree(a1[i1]);
                
                if(p.left==null){
                    p.left=q;
                    q.parent=p;
                }
                else if(p.right==null){
                    p.right=q;
                    q.parent=p;
                }
                else{
                    while(p.right!=null)p=p.parent;
                    p.right=q;
                    q.parent=p;
                }
                p=q;
                
            }
            else{
                q=new J_Tree(a1[i1]);
                if(q.element-'0'>=0&&q.element-'9'<=9)
                q.N=q.element-'0';
                if(p.left==null){
                    p.left=q;
                }
                else if(p.right==null){
                    p.right=q;
                }
                else{
                    while(p.right!=null)p=p.parent;
                    p.right=q;
                }
                    
            }
        }
        return root;
    }
    public static void run(J_Tree o){
        J_Tree p;
        int k=0;
        p=o;
        if(p==null) return;
        if(p.left!=null){
            if(p.left.element=='+'||p.left.element=='-'||p.left.element=='*'||
                    p.left.element=='/'||p.left.element=='^')
                if(((p.left.element=='+'||p.left.element=='-')&&(p.element=='*'||p.element=='/'||p.element=='^'))
                ||((p.left.element=='*'||p.left.element=='/')&&p.element=='^')) {
                    a[i]='(';
                    i++;
                    run(p.left);
                    a[i]=')';
                    i++;
                }
                else{run(p.left);}
            else{
                run(p.left);
            }           
        }
        if(p.element!='@'){
            a[i]=p.element;
            i++;
        }
        else{
            a[i]='@';
            c[i]=p.N;
            i++;
        }
            if((p.element-'0'>=0&&p.element-'0'<=9)||p.element=='+'||p.element=='-'||
                    p.element=='*'||p.element=='/'||p.element=='^'){}
            else{
                for(int i2=0;i2<j;i2++){
                    if(b[i2]==p.element){
                        k=1;
                        break;
                    }
                }
                if(k==0){
                    b[j]=p.element;
                    j++;
                }
                
            }
        if(p.right!=null){
            if(p.right.element=='+'||p.right.element=='-'||p.right.element=='*'||
                    p.right.element=='/'||p.right.element=='^')
                if(((p.right.element=='+'||p.right.element=='-')&&(p.element=='*'||p.element=='/'||p.element=='^'||p.element=='+'||p.element=='-'))
                ||((p.right.element=='*'||p.right.element=='/')&&(p.element=='^'||p.element=='*'||p.element=='/'))
                ||(p.right.element=='^'&&p.element=='^')) {
                    a[i]='(';
                    i++;
                    run(p.right);
                    a[i]=')';
                    i++;
                }else{run(p.right);}
            else{
                run(p.right);
            }           
        }
    }
   
    public static String WriteExpr(J_Tree o){
        String s;
        a=new char[100];
        b=new char[100];
        c=new double[100];
        zh=new String[100];
        for(int i=0;i<100;i++) zh[i]="未赋值";
        i=0;j=0;
        run(o);
        s=new String("");
        for(int k=0;k<i;k++){
            if(a[k]=='@') s=s.concat(""+c[k]);
            else s=s.concat(new String(a,k,1));
        }
       // s=new String(a,0,i);    
        return s;
    }
 
    public static double Value(J_Tree o){
        if(o.element=='+') return(Value(o.left)+Value(o.right));
        else if(o.element=='-') return(Value(o.left)-Value(o.right));
        else if(o.element=='*') return(Value(o.left)*Value(o.right));
        else if(o.element=='/') return(Value(o.left)/Value(o.right));
        else if(o.element=='^') return(java.lang.Math.pow(Value(o.left),Value(o.right)));
        else if(o.element-'0'>=0&&o.element-'0'<=9) return(o.element-'0');
        else{
            for(int i=0;i<j;i++)
                if(o.element==b[i]) {
                    return(java.lang.Double.parseDouble(zh[i]));
                }     
        }
        return 0;
    }
    public static J_Tree hebing(J_Tree o1,J_Tree o2,int o){
        
        if(o==0) root=new J_Tree('+');
        else if(o==1) root=new J_Tree('-');
        else if(o==2) root=new J_Tree('*');
        else if(o==3) root=new J_Tree('/');
        else  root=new J_Tree('^');
        root.left=o1;
        root.right=o2;
        return root;
    }
    public static J_Tree bing (J_Tree q){
        char em;
        J_Tree p1=null,p2=null;
        if(q.left!=null) p1=bing(q.left);
        if(q.right!=null) p2=bing(q.right);
        
        if(q.left!=null&&q.right!=null&&p1.N<10000&&p2.N<10000){
            em=q.element;
            if(em=='+'){
                q.element='@';
                q.N=p1.N+p2.N;
                q.left=null;
                q.right=null;     
            }
            else if(em=='-'){
                q.element='@';
                q.N=p1.N-p2.N;
                q.left=null;
                q.right=null;     
            }
            else if(em=='*'){
                q.element='@';
                q.N=p1.N*p2.N;
                q.left=null;
                q.right=null;     
            }
            else if(em=='/'){
                q.element='@';
                q.N=p1.N/p2.N;
                q.left=null;
                q.right=null;     
            }
            else if(em=='^'){
                q.element='@';
                q.N=java.lang.Math.pow(p1.N,p2.N);
                q.left=null;
                q.right=null;     
            }
            
        }
        return q;
        
    }
    
    public static String chang(J_Tree o){
        J_Tree p=o;
        bing(p);
        return WriteExpr(p);
    }
    

}