Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

New to MATLAB?

Problem 514. Spot the rectangle (Part 2)

Created by Ned Gulley

This problem is related to the 17x17 challenge. See also Part 1 of this problem. Given a matrix in which each element is either 1, 2, 3, or 4, determine whether or not any rectangles are present. A rectangle is a formed whenever four instances of the same value appear in the corners of a rectangular region of the matrix.

Examples:

 Input  a = [ 4 1 2 4 1
              3 3 2 1 4
              3 2 4 1 1
              1 4 3 2 2
              1 1 1 4 4 ]
 Output tf is false

You can't form any rectangles here.

 Input a = [ 1 4 3 1
             3 1 4 1
             1 3 4 1
             1 1 2 3 ]
 Output tf is true

There is a rectangle: a([1 3],[1 4]) is [1 1; 1 1]

Tags

Problem Group

Solution Statistics

26 correct solutions 12 incorrect solutions
Last solution submitted on Mar 05, 2015

Problem Comments