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SRM25 May 2011
SRM 521

SquaredSubsets

Problem statement, definition, constraints, and public examples.

Problem Statement

Given a set of points in the XY plane and an integer n, a subset P of those points is called n-squared if it is not empty and there exists a square of side n in the XY plane with its sides parallel to the axes such that a point from the given set of points is in P if and only if it is contained within the square. A point lying on a side or a vertex of the square is considered to be contained in it.

You will be given n as explained in the input. You will also be given two int[]s x and y such that the coordinates of point i are (x[i],y[i]). Return the number of n-squared subsets in the input set described by x and y.

Definition

Class:
SquaredSubsets
Method:
countSubsets
Parameters:
int, int[], int[]
Returns:
long
Method signature:
long countSubsets(int n, int[] x, int[] y)
(be sure your method is public)

Constraints

  • n will be between 1 and 100000000 (10^8), inclusive.
  • x and y will contain between 1 and 50 elements, inclusive.
  • x and y will contain the same number of elements.
  • Each element of x and y will be between -100000000 (-10^8) and 100000000 (10^8), inclusive.
  • All described points will be different.

Examples

  1. 5
    {-5,0,5}
    {0,0,0}
    Returns: 5
    The following subsets are squared: {(-5,0)}, {(0,0)}, {(5,0)}, {(-5,0),(0,0)}, {(0,0),(5,0)}.
  2. 10
    {-5,0,5}
    {0,0,0}
    Returns: 5
    The following subsets are squared: {(-5,0)}, {(5,0)}, {(0,0),(5,0)}, {(-5,0),(0,0)}, {(-5,0),(0,0),(5,0)}.
  3. 100000000
    {-1,-1,-1,0,1,1,1}
    {-1,0,1,1,-1,0,1}
    Returns: 21
  4. 5
    {5,3,6,2,1,6,4,4,7,-1,-4,-7,2,-2,0}
    {0,-1,8,-5,2,5,-8,8,-6,4,3,2,7,3,5}
    Returns: 66
  5. 1
    {-1,0}
    {0,0}
    Returns: 3
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