#include #include #define MaxSize 100 typedef char ElemType; typedef struct node { ElemType data; int ltag,rtag; //增加的線索標(biāo)記 struct node *lchild; struct node *rchild; } TBTNode; void CreateTBTNode(TBTNode * &b,char *str) { TBTNode *St[MaxSize],*p=NULL; int top=-1,k,j=0; char ch; b=NULL; //建立的2叉樹初始時(shí)為空 ch=str[j]; while (ch!=?) //str未掃描完時(shí)循環(huán) { switch(ch) { case (: top++; St[top]=p; k=1; break; //為左結(jié)點(diǎn) case ): top--; break; case ,: k=2; break; //為右結(jié)點(diǎn) default: p=(TBTNode *)malloc(sizeof(TBTNode)); p->data=ch; p->lchild=p->rchild=NULL; if (b==NULL) //*p為2叉樹的根結(jié)點(diǎn) b=p; else //已建立2叉樹根結(jié)點(diǎn) { switch(k) { case 1: St[top]->lchild=p; break; case 2: St[top]->rchild=p; break; } } } j++; ch=str[j]; } } void DispTBTNode(TBTNode *b) { if (b!=NULL) { printf("%c",b->data); if (b->lchild!=NULL || b->rchild!=NULL) { printf("("); DispTBTNode(b->lchild); if (b->rchild!=NULL) printf(","); DispTBTNode(b->rchild); printf(")"); } } } TBTNode *pre; //全局變量 void Thread(TBTNode *&p) { if (p!=NULL) { Thread(p->lchild); //左子樹線索化 if (p->lchild==NULL) //先驅(qū)線索 { p->lchild=pre; //建立當(dāng)前結(jié)點(diǎn)的先驅(qū)線索 p->ltag=1; } else p->ltag=0; if (pre->rchild==NULL) //后繼線索 { pre->rchild=p; //建立先驅(qū)結(jié)點(diǎn)的后繼線索 pre->rtag=1; } else pre->rtag=0; pre=p; Thread(p->rchild); //右子樹線索化 } } TBTNode *CreaThread(TBTNode *b) //中序線索化2叉樹 { TBTNode *root; root=(TBTNode *)malloc(sizeof(TBTNode)); //創(chuàng)建根結(jié)點(diǎn) root->ltag=0; root->rtag=1; root->rchild=b; if (b==NULL) //空2叉樹 root->lchild=root; else { root->lchild=b; pre=root; //pre是*p的先驅(qū)結(jié)點(diǎn),供加線索用 Thread(b); //中序遍歷線索化2叉樹 pre->rchild=root; //最后處理,加入指向根結(jié)點(diǎn)的線索 pre->rtag=1; root->rchild=pre; //根結(jié)點(diǎn)右線索化 } return root; } void ThInOrder(TBTNode *tb) { TBTNode *p=tb->lchild; //指向根結(jié)點(diǎn) while (p!=tb) { while (p->ltag==0) p=p->lchild; printf("%c ",p->data); while (p->rtag==1 && p->rchild!=tb) { p=p->rchild; printf("%c ",p->data); } p=p->rchild; } } int main() { TBTNode *b,*tb; CreateTBTNode(b,"A(B(D(,G)),C(E,F))"); printf(" 2叉樹:"); DispTBTNode(b); printf(" "); tb=CreaThread(b); printf(" 線索中序序列:"); ThInOrder(tb); printf(" "); return 0; }