二叉树表达式求值.docx

1、二叉树表达式求值二叉树表达式求值本文由邓志光8贡献/二叉树上的表达式求值算法#include #include #include #define max 100typedef structchar *data;int top;int stacksize;seqstack1;typedef struct Treechar data1max;float data2;struct Tree *lchild,*rchild;*BiTree,Bnode;typedef struct BiTree *data;int top;int stacksize;seqstack2; /运算符栈int initst

2、ack1(seqstack1 &L)L.data=(char *)malloc(max * sizeof(char);if(L.data=NULL) exit(0);L.top=-1;L.stacksize=max;return 1;int pushstack1(seqstack1 &L,char ch)if(L.top=L.stacksize-1)printf(栈满!n); return 0;L.top+;L.dataL.top=ch;return 1;char popstack1(seqstack1 &L)if(L.top=-1)printf(空栈!n);elsereturn L.data

3、L.top-;char gettop1(seqstack1 L)if(L.top=-1)printf(!空栈!n);elsereturn L.dataL.top;/操作数栈int initstack2(seqstack2 &L)L.data=(BiTree *)malloc(max * sizeof(BiTree);if(L.data=NULL) exit(0);L.top=-1;L.stacksize=max;return 1;int pushstack2(seqstack2 &L,BiTree T)if(L.top=L.stacksize-1)printf(栈满!n); return 0;

4、L.top+;L.dataL.top=T;return 1;int popstack2(seqstack2 &L,BiTree &T)if(L.top=-1)printf(?空栈!n); return 0;T=L.dataL.top;L.top-;return 1;int gettop2(seqstack2 L,BiTree &T)if(L.top=-1)printf(空栈!n); return 0;T=L.dataL.top;return 1;/求值栈int prior(char str1,char str2)switch(str1)case #:case(:case:return 0;br

5、eak;case *:case /:return 1;break;case +:case-:switch(str2)case +:case-:case#:return 1;break;case *:case /:return 0;break;break;int indigit(char ch)if(ch=0&ch=0&chidata1,ch);T-data2=n;T-lchild=T-rchild=NULL;pushstack2(L2,T);/建子树void createtree(BiTree &T,char *ch,BiTree rchild,BiTree lchild,seqstack2

6、&L2) float n;ch1=0;T=(Bnode *)malloc(sizeof(Bnode);if(T=NULL) exit(0);popstack2(L2,rchild); popstack2(L2,lchild);n=calculate(lchild-data2,rchild-data2,ch);T-data2=n; strcpy(T-data1,ch);T-rchild=rchild; T-lchild=lchild;pushstack2(L2,T);/表达式转换为二叉树存储BiTree Tobitree(char *p)seqstack1 L1;seqstack2 L2;int

7、 i=0,j=0;BiTree T,lchild,rchild;char str20,ch;initstack1(L1); pushstack1(L1,#); initstack2(L2);while(pi!=0) if(indigit(pi)while(indigit(pi)strj+=pi;i+;strj=0;createleaf(T,str,L2);j=0; i-;elseswitch(pi)case (:case :pushstack1(L1,pi);break;case ):ch=popstack1(L1);while(ch!=()createtree(T,&ch,rchild,lc

8、hild,L2); ch=popstack1(L1);break;case :ch=popstack1(L1);while(ch!=)createtree(T,&ch,rchild,lchild,L2); ch=popstack1(L1);break;default:ch=gettop1(L1);while(prior(ch,pi)createtree(T,&ch,rchild,lchild,L2); ch=popstack1(L1); ch=gettop1(L1);pushstack1(L1,pi);break;i+;popstack2(L2,T);return T;/后序遍历表达式树voi

9、d postorder(BiTree T)if(T)postorder(T-lchild);postorder(T-rchild);printf(%s ,T-data1);/先序遍历表达式树void midorder(BiTree T)if(T)midorder(T-lchild);printf(%s ,T-data1);midorder(T-rchild);void main()char *p;BiTree T;p=(char *)malloc(max * sizeof(char);printf(输入表达式(以#号结束):);scanf(%s,p);T=Tobitree(p);printf(后缀式为:);postorder(T);printf(n);printf(前缀式为);midorder(T);printf(n);printf(结果为:);printf(%.3fn,T-data2);