Given a positive integer n. The problem is to print the pyramid pattern as described in the examples below.
Examples:
Input : n = 4 Output : 1 3*2 4*5*6 10*9*8*7 Input : n = 5 Output : 1 3*2 4*5*6 10*9*8*7 11*12*13*14*15
Source: Amdocs Interview Experience | Set 1
Approach: For odd number row, values are being displayed in increasing order and for even number row, values are being displayed in decreasing order. The only other trick is to how to iterate the loops.
Algorithm:
printPattern(int n)
Declare j, k
Initialize k = 0
for i = 1 to n
if i%2 != 0
for j = k+1, j < k+i, j++
print j and "*"
print j and new line
k = ++j
else
k = k+i-1
for j = k, j > k-i+1, j--
print j and "*";
print j and new line
C++
// C++ implementation to print the following // pyramid pattern #include <bits/stdc++.h> using namespace std; // function to print the following pyramid pattern void printPattern(int n) { int j, k = 0; // loop to decide the row number for (int i=1; i<=n; i++) { // if row number is odd if (i%2 != 0) { // print numbers with the '*' sign in // increasing order for (j=k+1; j<k+i; j++) cout << j << "*"; cout << j++ << endl; // update value of 'k' k = j; } // if row number is even else { // update value of 'k' k = k+i-1; // print numbers with the '*' in // decreasing order for (j=k; j>k-i+1; j--) cout << j << "*"; cout << j << endl; } } } // Driver program to test above int main() { int n = 5; printPattern(n); return 0; } |
Java
// Java implementation to print the // following pyramid pattern public class Pyramid_Pattern { // function to print the following pyramid // pattern static void printPattern(int n) { int j, k = 0; // loop to decide the row number for (int i = 1; i <= n; i++) { // if row number is odd if (i % 2 != 0) { // print numbers with the '*' // sign in increasing order for (j = k + 1; j < k + i; j++) System.out.print(j + "*"); System.out.println(j++); // update value of 'k' k = j; } // if row number is even else { // update value of 'k' k = k + i - 1; // print numbers with the '*' in // decreasing order for (j = k; j > k - i + 1; j--) System.out.print(j + "*"); System.out.println(j); } } } // Driver program to test above public static void main(String args[]) { int n = 5; printPattern(n); } } // This code is contributed by Sumit Ghosh |
Python3
# Python3 implementation to print the # following pyramid pattern # function to print the # following pyramid pattern def printPattern(n) : j, k = 0, 0 # loop to decide the row number for i in range(1, n + 1) : # if row number is odd if i % 2 != 0 : # print numbers with # the '*' sign in # increasing order for j in range(k + 1, k + i) : print(str(j) + "*", end = "") j = k + i print(j) j += 1 # update value of 'k' k = j # if row number is even else : # update value of 'k' k = k + i - 1 # print numbers with the # '*' in decreasing order for j in range(k, k - i + 1, -1) : print(str(j) + "*", end = "") j = k - i + 1 print(j) # Driver Code if __name__ == "__main__" : n = 5 # function calling printPattern(n) # This code is contributed # by ANKITRAI1 |
C#
// C# implementation to print the // following pyramid pattern using System; public class Pyramid_Pattern { // function to print the following pyramid // pattern static void printPattern(int n) { int j, k = 0; // loop to decide the row number for (int i = 1; i <= n; i++) { // if row number is odd if (i % 2 != 0) { // print numbers with the '*' // sign in increasing order for (j = k + 1; j < k + i; j++) Console.Write(j + "*"); Console.WriteLine(j++); // update value of 'k' k = j; } // if row number is even else { // update value of 'k' k = k + i - 1; // print numbers with the '*' in // decreasing order for (j = k; j > k - i + 1; j--) Console.Write(j + "*"); Console.WriteLine(j); } } } // Driver program to test above public static void Main() { int n = 5; printPattern(n); } } // This code is contributed by vt_m. |
PHP
<?php // PHP implementation to print the // following pyramid pattern // function to print the following // pyramid pattern function printPattern($n) { $k = 0; // loop to decide // the row number for ($i = 1; $i <= $n; $i++) { // if row number is odd if ($i % 2 != 0) { // print numbers with the '*' // sign in increasing order for ($j = $k + 1; $j < $k + $i; $j++) echo $j. "*"; echo $j++ ."\n"; // update value of 'k' $k = $j; } // if row number is even else { // update value of 'k' $k = $k + $i - 1; // print numbers with the // '*' in decreasing order for ($j = $k; $j > $k - $i + 1; $j--) echo $j . "*"; echo $j ."\n" ; } } } // Driver Code $n = 5; printPattern($n); // This code is contributed by Sam007 ?> |
Javascript
<script> // JavaScript implementation to print the // following pyramid pattern // Function to print the following // pyramid pattern function printPattern(n) { var j, k = 0; // Loop to decide the row number for(var i = 1; i <= n; i++) { // If row number is odd if (i % 2 != 0) { // Print numbers with the '*' // sign in increasing order for(j = k + 1; j < k + i; j++) document.write(j + "* "); document.write(j++ + "<br>"); // Update value of 'k' k = j; } // If row number is even else { // Update value of 'k' k = k + i - 1; // Print numbers with the '*' in // decreasing order for(j = k; j > k - i + 1; j--) document.write(j + "*"); document.write(j + "<br>"); } } } // Driver code var n = 5; printPattern(n); // This code is contributed by akshitsaxenaa09 </script> |
Output:
1 3*2 4*5*6 10*9*8*7 11*12*13*14*15
Time Complexity: O((n * (n + 1)) / 2)
Space Complexity: O(1) since using constant variables, since no extra space has been taken.
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