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tretest.cpp
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tretest.cpp
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#include <iostream>
#include <vector>
#include <stack>
#include <queue>
using namespace std;
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
TreeNode* createTree(int a[], int n)
{
if (n<=0) return NULL;
TreeNode **tree = new TreeNode*[n];
for(int i=0; i<n; i++) {
tree[i] = new TreeNode(a[i]);
}
int pos=1;
for(int i=0; i<n && pos<n; i++) {
if (tree[i])
{
tree[i]->left = tree[pos++];
if (pos<n)
{
tree[i]->right = tree[pos++];
}
}
}
return tree[0];
}
void printTree_post_order(TreeNode *root)
{
if (root == NULL){
//cout << "# ";
return ;
}
printTree_post_order(root->left);
printTree_post_order(root->right);
cout << root->val << " ";
}
void printTree_bylevel(TreeNode* root)
{
if(!root) return;
queue<TreeNode*> q;
q.push(root);
q.push(NULL);
int pos = 18;
for(int i = 0; i < pos; ++i)
{
cout << " ";
}
pos = 0;
while(!q.empty())
{
TreeNode* p = q.front(); q.pop();
if(p)
{
cout << p -> val << " ";
if( p -> left) q.push( p-> left);
if( p -> right) q.push( p -> right);
pos +=1;
}
else
{
if(q.empty()) return;
q.push(NULL);
cout << endl;
for(int i = 0; i < 18 - pos; ++i)
{
cout << " ";
}
}
}
}
vector<int> visibNodes(TreeNode *root)
{
// visible nodes: in the ppath from root to the current node, there is
// no node whose value exceeds the current one's.
vector<int> result;
if(!root) return result;
stack<int > pathValue;
stack<int > maxValue;
maxValue.push(INT_MIN);
stack<TreeNode* > s;
TreeNode *last = NULL;
while(!s.empty() || root)
{
if(root)
{
s.push(root);
pathValue.push(root -> val);
if(root -> val >= maxValue.top())
{
maxValue.push(root -> val);
}
root = root -> left;
}
else
{
TreeNode* peak = s.top();
if(peak -> right && last != peak -> right)
{
root = peak -> right;
}
else
{
last = peak;
if(peak -> val >= maxValue.top())
{
result.push_back(peak -> val);
maxValue.pop();
}
pathValue.pop();
s.pop();
}
}
}
return result;
}
void printArray(vector<int> v)
{
for(int i=0; i<v.size(); i++){
cout << v[i] << " ";
}
cout << endl;
}
int main(int argc, const char * argv[]) {
int a[] = {5, 3, 20, 21, 7, 12, 8};
TreeNode* p = createTree(a, sizeof(a)/sizeof(int));
cout <<"nodes in post order traversal: " << endl;
printTree_post_order(p);
cout << endl;
cout << "nodes in traversal by level: " << endl;
printTree_bylevel(p);
cout << endl;
vector<int> v = visibNodes(p);
cout << "visible nodes: "<<endl;
printArray(v);
cout << endl;
return 0;
}