Given a number N(? 8), the task is to print a Hollow Triangle inside a Triangle pattern.
Example:
Input: N = 9
Output:
*
* *
* *
* * *
* * * * *
* *
* *
* *
* * * * * * * * * * * * * * * * *
Approach:
Let i be the index for rows and j be the index for columns. Then:
- For sides of outer triangle:
If the index of column(j) is equals to (N – i + 1) or (N + i – 1), then ‘*’ is printed for equal sides of outer triangle.
if(j == (N - i + 1)
|| j == (N + i - 1) {
print('*')
}
- For sides of inner triangle:
If the (index of row(i) is less than (N – 4) and greater than (4) and index of column(j) is equals to (N – i + 4) or (N + i + 4), then ‘*’ is printed for equal sides of inner triangle.
if( (i >= 4
&& i <= n - 4)
&& (j == N - i + 4
|| j == N + i - 4) ) {
print('*')
}
- For bases of the outer triangle:
If the index of row(i) is equal to N, then ‘*’ is printed for the base of outer triangle.
if(i == N) {
print('*')
}
- For bases of the inner triangle:
If the index of row(i) is equals (N – 4) and the column index(j) must be greater than equals to (N – (N – 2*4)), and j is less than equals to (N + N – 2*4), then ‘*’ is printed for the base of inner triangle.
if( (i == N - 4)
&& (j >= N - (N - 2 * 4) )
&& (j <= n + n - 2 * 4) ) ) {
print('*')
}
Below is the implementation of the above approach:
CPP
// C++ implementation of the above approach#include <bits/stdc++.h>using namespace std;// Function to print the patternvoid printPattern(int n){ int i, j; // Loop for rows for (i = 1; i <= n; i++) { // Loop for column for (j = 1; j < 2 * n; j++) { // For printing equal sides // of outer triangle if (j == (n - i + 1) || j == (n + i - 1)) { cout << "* "; } // For printing equal sides // of inner triangle else if ((i >= 4 && i <= n - 4) && (j == n - i + 4 || j == n + i - 4)) { cout << "* "; } // For printing base // of both triangle else if (i == n || (i == n - 4 && j >= n - (n - 2 * 4) && j <= n + n - 2 * 4)) { cout << "* "; } // For spacing between the triangle else { cout << " " << " "; } } cout << "\n"; }}// Driver Codeint main(){ int N = 9; printPattern(N);} |
Java
// Java implementation of the above approachimport java.util.*;class GFG{ // Function to print the patternstatic void printPattern(int n){ int i, j; // Loop for rows for (i = 1; i <= n; i++) { // Loop for column for (j = 1; j < 2 * n; j++) { // For printing equal sides // of outer triangle if (j == (n - i + 1) || j == (n + i - 1)) { System.out.print("* "); } // For printing equal sides // of inner triangle else if ((i >= 4 && i <= n - 4) && (j == n - i + 4 || j == n + i - 4)) { System.out.print("* "); } // For printing base // of both triangle else if (i == n || (i == n - 4 && j >= n - (n - 2 * 4) && j <= n + n - 2 * 4)) { System.out.print("* "); } // For spacing between the triangle else { System.out.print(" " + " "); } } System.out.print("\n"); }} // Driver Codepublic static void main(String[] args){ int N = 9; printPattern(N);}}// This code is contributed by sapnasingh4991 |
Python3
# Python3 implementation of the above approach# Function to print the patterndef printPattern(n): # Loop for rows for i in range(1, n + 1): # Loop for column for j in range(1, 2 * n): # For printing equal sides # of outer triangle if (j == (n - i + 1) or j == (n + i - 1)): print("* ",end="") # For printing equal sides # of inner triangle elif ((i >= 4 and i <= n - 4) and (j == n - i + 4 or j == n + i - 4)): print("* ",end="") # For printing base # of both triangle elif (i == n or (i == n - 4 and j >= n - (n - 2 * 4) and j <= n + n - 2 * 4)): print("* ", end="") # For spacing between the triangle else : print(" "+" ", end="") print()# Driver CodeN = 9printPattern(N)# This code is contributed by mohit kumar 29 |
C#
// C# implementation of the above approachusing System;class GFG{ // Function to print the patternstatic void printPattern(int n){ int i, j; // Loop for rows for (i = 1; i <= n; i++) { // Loop for column for (j = 1; j < 2 * n; j++) { // For printing equal sides // of outer triangle if (j == (n - i + 1) || j == (n + i - 1)) { Console.Write("* "); } // For printing equal sides // of inner triangle else if ((i >= 4 && i <= n - 4) && (j == n - i + 4 || j == n + i - 4)) { Console.Write("* "); } // For printing base // of both triangle else if (i == n || (i == n - 4 && j >= n - (n - 2 * 4) && j <= n + n - 2 * 4)) { Console.Write("* "); } // For spacing between the triangle else { Console.Write(" " + " "); } } Console.Write("\n"); }} // Driver Codepublic static void Main(String[] args){ int N = 9; printPattern(N);}}// This code is contributed by 29AjayKumar |
Javascript
<script> // JavaScript implementation of the above approach // Function to print the pattern function printPattern(n) { var i, j; // Loop for rows for (i = 1; i <= n; i++) { // Loop for column for (j = 1; j < 2 * n; j++) { // For printing equal sides // of outer triangle if (j == n - i + 1 || j == n + i - 1) { document.write("* "); } // For printing equal sides // of inner triangle else if ( i >= 4 && i <= n - 4 && (j == n - i + 4 || j == n + i - 4) ) { document.write("* "); } // For printing base // of both triangle else if ( i == n || (i == n - 4 && j >= n - (n - 2 * 4) && j <= n + n - 2 * 4) ) { document.write("* "); } // For spacing between the triangle else { document.write(" "); document.write(" "); } } document.write("<br>"); } } // Driver Code var N = 9; printPattern(N); </script> |
Output:
*
* *
* *
* * *
* * * * *
* *
* *
* *
* * * * * * * * * * * * * * * * *
Time Complexity: O(n2)
Auxiliary Space: O(1)
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