postorder tree traversal in cpp

String/calandar.cpp

@@ -0,0 +1,88 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Calender{
+	public :
+		int month, year;
+
+		Calender(int mo, int yr){
+			month = mo;
+			year = yr;
+		}
+
+		// Calender(){
+
+		// }
+		void Print_Month(){
+			PrintMonth(month, year);
+		}
+		int GetDays(int month, int year){
+			if( month == 2){
+				if((year % 400==0) || (year % 4 == 0 && year % 100 != 0))	
+					return 29;
+				else	
+					return 28;
+			}
+
+			else if(month == 1 || month == 3 || month == 5 || month == 7 || month == 8 ||month == 10 || month==12)	
+				return 31;
+			else 		
+				return 30;
+		} 
+
+	int MonthStartsOn(int mnth, int yr){
+		return 6;
+	}
+
+	void PrintMonth(int mnth, int yr){
+		int date = MonthStartsOn(mnth, yr), i, j, k;
+		int days = GetDays(mnth, yr);
+		char c = ' ';
+		cout << "Mon" << " " << "Tue" << " " << "Wed" << " " << "Thu" << " " << "Fri" << " " << "Sat" << " " << "Sun" << endl;
+		k = 1;
+		for(i = 0; i < 7; i ++){
+			if(i < date){
+				cout << c << c << c << c;
+			}
+			else{
+				cout << k++ << c << c << c;
+			}
+		}
+
+		cout << endl;
+		k = 8 - date;
+		while(k < 10){
+			for(i = 0; i < 7; i ++){
+				if(k > 9)
+					break;
+				cout << k << c << c << c; 
+				k ++;
+			}
+			if(i == 7)
+				cout << endl;
+		}
+		while(i != 7){
+			cout << k << c << c;
+			k ++;
+			i ++;
+		}
+		cout << endl;
+		while(k <= days){
+			for(i = 0; i < 7; i ++){
+				if(k > days)
+					break;
+				cout << k << c << c;
+				k ++;
+			}
+			cout << endl;
+		}
+	}
+};
+
+
+int main(){
+	Calender c;
+	c.PrintMonth(7, 2020);
+
+	return 0;
+}

Tree/postorder.cpp

@@ -0,0 +1,56 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+
+struct Node { 
+	int data; 
+	struct Node *left, *right; 
+}; 
+
+
+
+void POSTORDER(struct Node* head) 
+{ 
+	struct Node* temp = head; 
+	unordered_set<Node*> visited; 
+	while (temp && visited.find(temp) == visited.end()) { 
+
+
+		if (temp->left && 
+		visited.find(temp->left) == visited.end()) 
+			temp = temp->left; 
+
+		else if (temp->right && 
+		visited.find(temp->right) == visited.end()) 
+			temp = temp->right; 
+
+		else { 
+			printf("%d ", temp->data); 
+			visited.insert(temp); 
+			temp = head; 
+		} 
+	} 
+} 
+
+struct Node* newNode(int data) 
+{ 
+	struct Node* node = new Node; 
+	node->data = data; 
+	node->left = NULL; 
+	node->right = NULL; 
+	return (node); 
+} 
+
+int main() 
+{ 
+	struct Node* root = newNode(8); 
+	root->left = newNode(2); 
+	root->right = newNode(9); 
+	root->left->left = newNode(3); 
+	root->left->right = newNode(5); 
+	root->left->right->left = newNode(6); 
+	root->left->right->right = newNode(4); 
+	root->right->right = newNode(7); 
+	root->right->right->left = newNode(13); 
+	POSTORDER(root); 
+	return 0; 
+} 

Vector/vector.cpp

@@ -0,0 +1,23 @@
+#include<iostream>
+using namespace std;
+#include<bits/stdc++.h>
+#include<vector>
+int main(){
+    vector <int> v {10,20,40};
+    cout<<v[0]<<" ";
+
+    vector <string> v1 {"aawesh","patanwala"};
+    cout<<v1[0]<<" ";
+
+    vector <char> v4 {'A','B'};
+    cout<<v4[0]<<" ";
+
+    vector <char> v3 {5};                          //created a vector of size 5, type char
+    v3[0] = 'A';
+    v3[1] = 'B';
+    v3[2] = 'C';
+    v3[3] = 'D';
+    v3[4] = 'E';
+    cout<<v3[0]<<" "<<v3[1]<<" "<<v3[2]<<" "<<v3[3]<<" "<<v3[4]<<" "<<endl;
+    cout<<"ok";
+}

removeDuplicate.cpp

@@ -0,0 +1,34 @@
+//remove Duplicate
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int arr[1000], n, i, j;
+
+    cin>>n;
+
+    for(i=0; i<n; i++){
+        cin>>arr[i];
+    }
+
+    for(i=0; i<n; i++){
+        for(j=0; j<n; j++){
+            if(arr[i] != arr[i+1]){
+                cout<<arr[i]<<" ";
+                cout<<arr[j]<<" ";
+            }
+            else{
+                cout<<i<<" ";
+            }
+
+            //i++;
+            //j++;
+
+        }
+    }
+
+    for(i=0; i<n; i++){
+        cout<<arr[i]<<" ";
+    }
+
+}