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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.     public static int[] histogram(final int min, final int max, final int bucket, final int count) {
  11.         // note, in this method, there's no need to know the actual values, just the range.
  12.         final int range = max - min + 1;
  13.         final int buckets = (range + bucket - 1) / bucket;
  14.         final int[] results = new int[buckets];
  15.         final Random rand = new Random();
  16.         for (int i = 0; i < count; i++) {
  17.             int value = rand.nextInt(range);
  18.             results[value / bucket]++;
  19.         }
  20.         return results;
  21.     }
  22.  
  23.     public static void displayHistogram(final int first, final int bucketsize, final int maxbar, final int[] buckets) {
  24.         int maxcount = getMax(buckets);
  25.         int scale = ((maxcount + maxbar - 1) / maxbar) + 1;
  26.         int width = (maxcount + scale - 1) / scale;
  27.         String format = "%5d-%-5d | %-" + width + "s | %d\n";
  28.         for (int i = 0; i < buckets.length; i++) {
  29.             int start = (bucketsize * i) + first;
  30.             int end = start + bucketsize - 1;
  31.             System.out.printf(format, start, end, buildAsterisks(buckets[i], scale), buckets[i]);
  32.         }
  33.  
  34.  
  35.         System.out.printf("%11s | %s\n", "", lines(width));
  36.         System.out.printf("%-11s | %s\n", "Scale", marks(maxcount, scale));
  37.  
  38.     }    
  39.  
  40.     private static int getMax(int[] buckets) {
  41.         int max = 0;
  42.         for (int val : buckets) {
  43.             max = Math.max(max,  val);
  44.         }
  45.         return max;
  46.     }
  47.  
  48.     private static Object marks(int maxcount, int scale) {
  49.         int width = (int)Math.log10(maxcount - 1) + 2;
  50.         int count = ((maxcount + scale - 1) / scale) / width;
  51.         StringBuilder sb = new StringBuilder();
  52.         int mark = 0;
  53.         int step = scale * width;
  54.         for (int i = 0; i < count; i++) {
  55.             mark += step;
  56.             sb.append(String.format("%" + width + "d", mark));
  57.         }
  58.         return sb.toString();
  59.     }
  60.  
  61.     private static String lines(int width) {
  62.         char[] array = new char[width];
  63.         Arrays.fill(array, '-');
  64.         return new String(array);
  65.     }
  66.  
  67.     private static String buildAsterisks(int size, int scale) {
  68.         char[] array = new char[(size + scale - 1) / scale];
  69.         Arrays.fill(array, '*');
  70.         return new String(array);
  71.     }
  72.  
  73.     public static void main(String[] args) {
  74.         int min = 1;
  75.         int max = 100;
  76.         int bsize = 10;
  77.         int[] buckets = histogram(min, max, bsize, 1000);
  78.         displayHistogram(min, bsize, 40, buckets);
  79.     }
  80.  
  81. }
Success #stdin #stdout 0.08s 380160KB
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stdin
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Standard input is empty
stdout
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    1-10    | *********************         | 84
   11-20    | **************************    | 102
   21-30    | ***************************** | 114
   31-40    | *************************     | 100
   41-50    | *************************     | 100
   51-60    | ************************      | 95
   61-70    | ************************      | 94
   71-80    | ***************************** | 113
   81-90    | ***********************       | 92
   91-100   | ***************************   | 106
            | -----------------------------
Scale       |   16  32  48  64  80  96 112
https://ideone.com/O9k6EX
language:
Java (12.0.1)
created:
9 years ago
visibility:
public

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