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  • [转]根据二叉树的先序、中序遍历结果重建二叉树

        #include <stdlib.h> 
        #include <stdio.h> 
         
        typedef struct TNode 
        { 
            int value; 
            TNode* lchild; 
            TNode* rchild; 
        }TNode,*BTree;  
         
        //根据先序遍历、中序遍历构建二叉树 
        BTree rebuild(int preOrder[],int startPre,int endPre,int inOrder[],int startIn,int endIn) 
        { 
            //先序遍历和中序遍历长度应相等 
            if (endPre - startPre != endIn - startIn) return NULL; 
            //起始位置不应大于末尾位置 
            if (startPre > endPre) return NULL; 
            //先序遍历的第一个元素为根节点 
            BTree tree = (BTree)malloc(sizeof(TNode)); 
            tree->value = preOrder[startPre]; 
            tree->lchild = NULL; 
            tree->rchild = NULL; 
            //先序遍历和中序遍历只有一个元素时,返回该节点 
            if (startPre == endPre) return tree; 
            //在中序遍历中找到根节点 
            int index,length; 
            for (index=startIn;index<=endIn;index++) 
            { 
                if (inOrder[index] == preOrder[startPre]) break; 
            } 
            //若未找到,返回空 
            if (index > endIn) return NULL; 
            //有左子树,递归调用构建左子树 
            if (index > startIn)  
            { 
                length = index-startIn; 
                tree->lchild = rebuild(preOrder,startPre+1,startPre+1+length-1,inOrder,startIn,startIn+length-1); 
            } 
            //有右子树,递归调用构建右子树 
            if (index < endIn)  
            { 
                length = endIn - index; 
                tree->rchild = rebuild(preOrder,endPre-length+1,endPre,inOrder,endIn-length+1,endIn); 
            } 
            return tree; 
        } 
         
        //后序遍历二叉树 
        void postTraverse(BTree tree) 
        { 
            if (tree->lchild != NULL) postTraverse(tree->lchild); 
            if (tree->rchild != NULL) postTraverse(tree->rchild); 
            printf("%d ",tree->value); 
        } 
         
        int main() 
        { 
            int preOrder[] = {1,2,4,5,3,6}; 
            int inOrder[] = {4,2,5,1,6,3}; 
            BTree tree = rebuild(preOrder,0,5,inOrder,0,5); 
            postTraverse(tree); 
            printf("
    "); 
            return 0; 
        } 
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  • 原文地址:https://www.cnblogs.com/alexeyqian/p/3435742.html
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