Program to make a histogram of an array

02 Oct, 2017
Given an array of integers, print histogram of array values.
Examples:
Input : 0 11 2 13 5 12 8 11 12 9
Output :                  
13 |           x                   
12 |           x     x        x    
11 |     x     x     x     x  x    
10 |     x     x     x     x  x    
 9 |     x     x     x     x  x  x 
 8 |     x     x     x  x  x  x  x 
 7 |     x     x     x  x  x  x  x 
 6 |     x     x     x  x  x  x  x 
 5 |     x     x  x  x  x  x  x  x 
 4 |     x     x  x  x  x  x  x  x 
 3 |     x     x  x  x  x  x  x  x 
 2 |     x  x  x  x  x  x  x  x  x 
 1 |     x  x  x  x  x  x  x  x  x 
 0 |  x  x  x  x  x  x  x  x  x  x 
---------------------------------------
      0 11  2 13  5 12  8 11 12  9 


Input : 10 9 12 4 5 2 8 5 3 1
Output :                 
12 |        x                      
11 |        x                      
10 |  x     x                      
 9 |  x  x  x                      
 8 |  x  x  x           x          
 7 |  x  x  x           x          
 6 |  x  x  x           x          
 5 |  x  x  x     x     x  x       
 4 |  x  x  x  x  x     x  x       
 3 |  x  x  x  x  x     x  x  x    
 2 |  x  x  x  x  x  x  x  x  x    
 1 |  x  x  x  x  x  x  x  x  x  x 
 0 |  x  x  x  x  x  x  x  x  x  x 
---------------------------------------
     10  9 12  4  5  2  8  5  3  1

The idea is to print the given histogram row by row. For every element, we check if it is greater than or equal to current row. If yes, put a ‘x’ for that element. Else we put a space.
// CPP program to make histogram of an array#include <bits/stdc++.h>using namespace std;  void printHistogram(int arr[], int n){    int maxEle = *max_element(arr, arr + n);      for (int i = maxEle; i >= 0; i--) {        cout.width(2);        cout << right << i << " | ";        for (int j = 0; j < n; j++) {              // if array of element is greater            // then array it print x            if (arr[j] >= i)                cout << " x ";              // else print blank spaces            else                cout << "   ";        }        cout << "\n";    }      // print last line denoted by ----    for (int i = 0; i < n + 3; i++)        cout << "---";      cout << "\n";    cout << "     ";      for (int i = 0; i < n; i++) {        cout.width(2); // width for a number        cout << right << arr[i] << " ";    }}  // Driver codeint main(){    int arr[10] = { 10, 9, 12, 4, 5, 2,                    8, 5, 3, 1 };    int n = sizeof(arr) / sizeof(arr[0]);    printHistogram(arr, n);    return 0;}
Output:
                           
12 |        x                      
11 |        x                      
10 |  x     x                      
 9 |  x  x  x                      
 8 |  x  x  x           x          
 7 |  x  x  x           x          
 6 |  x  x  x           x          
 5 |  x  x  x     x     x  x       
 4 |  x  x  x  x  x     x  x       
 3 |  x  x  x  x  x     x  x  x    
 2 |  x  x  x  x  x  x  x  x  x    
 1 |  x  x  x  x  x  x  x  x  x  x 
 0 |  x  x  x  x  x  x  x  x  x  x 
---------------------------------------
     10  9 12  4  5  2  8  5  3  1

This article is contributed by Devanshu Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
pattern-printing
School Programming
pattern-printing
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.