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1020.cpp
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1020.cpp
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#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <vector>
#include <queue>
using namespace std;
struct node{
int val;
node *left;
node *right;
};
node* returnRoot(const vector<int> &poOrd, const vector<int> &inOrd, int poLeft, int poRight, int inLeft, int inRight) {
// cout << poLeft << " " << poRight << " " << inLeft << " " << inRight << endl;
if(poRight < poLeft || inRight < inLeft || poRight - poLeft != inRight - inLeft) {
return NULL;
}
node *root = new node;
root->val = poOrd[ poRight ];
int rootPos = 0, i = inLeft;
for(; i <= inRight; ++i) {
if(inOrd[i] == root->val)
break;
}
if(i > inRight) {
delete root;
return NULL;
}
rootPos = i;
int rightNum = inRight - rootPos, leftNum = rootPos - inLeft;
root->left = returnRoot(poOrd, inOrd, poLeft, poLeft + leftNum - 1, inLeft, inLeft + leftNum - 1);
root->right = returnRoot(poOrd, inOrd, poLeft + leftNum, poRight - 1, inLeft + leftNum + 1, inRight);
return root;
}
void levelOrder(node *root) {
if(NULL == root)
return;
vector<int> v;
queue<node*> q;
q.push(root);
while(q.size() != 0) {
if(q.front()->left != NULL)
q.push(q.front()->left);
if(q.front()->right != NULL)
q.push(q.front()->right);
v.push_back(q.front()->val);
q.pop();
}
printf("%d", v[0]);
for(int i = 1; i < v.size(); ++i) {
printf(" %d", v[i]);
}
printf("\n");
}
int main(int argc, char *argv[]) {
int n;
scanf("%d", &n);
if(n <= 0) {
return 0;
}
vector<int> poOrd(n, 0);
vector<int> inOrd(n, 0);
for(int i = 0; i < n; ++i) {
scanf("%d", &poOrd[i]);
}
for(int i = 0; i < n; ++i)
scanf("%d", &inOrd[i]);
int poRight = poOrd.size(), inRight = inOrd.size();
node *root = returnRoot(poOrd, inOrd, 0, poRight-1, 0, inRight-1);
// printf("%d\n", root->val);
levelOrder(root);
return 0;
}