# Ramanujan.java

Below is the syntax highlighted version of Ramanujan.java from §1.3 Conditionals and Loops.

```/******************************************************************************
*  Compilation:  javac Ramanujan.java
*  Execution:    java Ramanujan n
*
*  Prints out any number between 1 and n that can be expressed as the
*  sum of two cubes in two (or more) different ways.
*
*  % java Ramanujan 1728
*
*  % java Ramanujan 1729
*  1729 = 1^3 + 12^3 = 9^3 + 10^3
*
*  % java Ramanujan 10000
*  1729 = 1^3 + 12^3 = 9^3 + 10^3
*  4104 = 2^3 + 16^3 = 9^3 + 15^3
*
*  % java Ramanujan 100000
*  1729 = 1^3 + 12^3 = 9^3 + 10^3
*  4104 = 2^3 + 16^3 = 9^3 + 15^3
*  13832 = 2^3 + 24^3 = 18^3 + 20^3
*  39312 = 2^3 + 34^3 = 15^3 + 33^3
*  46683 = 3^3 + 36^3 = 27^3 + 30^3
*  32832 = 4^3 + 32^3 = 18^3 + 30^3
*  40033 = 9^3 + 34^3 = 16^3 + 33^3
*  20683 = 10^3 + 27^3 = 19^3 + 24^3
*  65728 = 12^3 + 40^3 = 31^3 + 33^3
*  64232 = 17^3 + 39^3 = 26^3 + 36^3
*
*  % java Ramanujan 100000000 | sort -n   // sort results numerically in Unix
*  1729 = 1^3 + 12^3 = 9^3 + 10^3
*  ...
*  87539319 = 167^3 + 436^3 = 228^3 + 423^3
*  87539319 = 167^3 + 436^3 = 255^3 + 414^3
*  87539319 = 228^3 + 423^3 = 255^3 + 414^3
*  ...
*
*  Bugs
*  ----
*  If a number can be expressed as a sum of cubes in more than two
*  different ways, the program prints some duplicates.
*
******************************************************************************/

public class Ramanujan {

public static void main(String[] args) {

// read in one command-line argument
int n = Integer.parseInt(args[0]);

// for each a, b, c, d, check whether a^3 + b^3 = c^3 + d^3
for (int a = 1; a <= n; a++) {
int a3 = a*a*a;
if (a3 > n) break;

// start at a to avoid print out duplicate
for (int b = a; b <= n; b++) {
int b3 = b*b*b;
if (a3 + b3 > n) break;

// start at a + 1 to avoid printing out duplicates
for (int c = a + 1; c <= n; c++) {
int c3 = c*c*c;
if (c3 > a3 + b3) break;

// start at c to avoid printing out duplicates
for (int d = c; d <= n; d++) {
int d3 = d*d*d;
if (c3 + d3 > a3 + b3) break;

if (c3 + d3 == a3 + b3) {
System.out.print((a3+b3) + " = ");
System.out.print(a + "^3 + " + b + "^3 = ");
System.out.print(c + "^3 + " + d + "^3");
System.out.println();
}
}
}
}
}
}
}
```