1086. Tree Traversals Again (25) PAT甲级

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#include<stdio.h>#include<queue>#include<string.h>#include<stack>using namespace std;#define MAX_N 37int inorder[MAX_N],preorder[MAX_N];typedef struct Node{    int data;    Node *lchild,*rchild;}node,*Btree;int n;void create(Btree &bt,int preL,int preR,int inL,int inR){    if(preL>preR){        bt=NULL;        return;    }    bt=new node;    bt->data=preorder[preL];    int leftnum;    int i;    for(i=inL;i<=inR;i++){        if(inorder[i]==preorder[preL]){            leftnum=i-inL;            break;        }    }    create(bt->lchild,preL+1,preL+leftnum,inL,i-1);    create(bt->rchild,preL+leftnum+1,preR,i+1,inR);}void postorder(Btree root){    static int count=0;    if(root==NULL)        return ;    postorder(root->lchild);    postorder(root->rchild);    printf("%d",root->data);    count++;    if(count<n) printf(" ");}int main(){    scanf("%d",&n);    char opr[5];    int num;    int preIndex=0,inIndex=0;    stack<int> s;    for(int i=0;i<2*n;i++){        scanf("%s",opr);        if(!strcmp(opr,"Push")){            scanf("%d",&num);            preorder[preIndex++]=num;            s.push(num);        }        else{            inorder[inIndex++]=s.top();            s.pop();        }    }    Btree root=NULL;    create(root,0,n-1,0,n-1);    postorder(root);}