Package edu.princeton.cs.algs4

Class ThreeSumFast

  • public class ThreeSumFast
extends Object
    The ThreeSumFast class provides static methods for counting and printing the number of triples in an array of distinct integers that sum to 0 (ignoring integer overflow).

    This implementation uses sorting and binary search and takes time proportional to n^2 log n, where n is the number of integers.

    For additional documentation, see Section 1.4 of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.

    Author:
    Robert Sedgewick, Kevin Wayne

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static int count​(int[] a)
      Returns the number of triples (i, j, k) with i < j < k such that a[i] + a[j] + a[k] == 0.
      static void main​(String[] args)
      Reads in a sequence of distinct integers from a file, specified as a command-line argument; counts the number of triples sum to exactly zero; prints out the time to perform the computation.
      static void printAll​(int[] a)
      Prints to standard output the (i, j, k) with i < j < k such that a[i] + a[j] + a[k] == 0.

    • Method Detail

      • printAll

        public static void printAll​(int[] a)
        Prints to standard output the (i, j, k) with i < j < k such that a[i] + a[j] + a[k] == 0.
        Parameters:
        a - the array of integers
        Throws:
        IllegalArgumentException - if the array contains duplicate integers

      • count

        public static int count​(int[] a)
        Returns the number of triples (i, j, k) with i < j < k such that a[i] + a[j] + a[k] == 0.
        Parameters:
        a - the array of integers
        Returns:
        the number of triples (i, j, k) with i < j < k such that a[i] + a[j] + a[k] == 0

      • main

        public static void main​(String[] args)
        Reads in a sequence of distinct integers from a file, specified as a command-line argument; counts the number of triples sum to exactly zero; prints out the time to perform the computation.
        Parameters:
        args - the command-line arguments