Remove duplicated triangles - MATLAB Cody - MATLAB Central

Problem 45230. Remove duplicated triangles

Difficulty:Rate

Input T is a triangulation (triplet list of indices -positive integers-, each index refering to a vertex number in a corresponding vertices list).

It sometimes happens a triangle may be duplicated several times. The goal of this problem is to remove all the duplicated triangles of T, and to keep only one.

For instance if :

T_in = [1 2 3;...
        4 5 6;...
        1 2 3;...
        7 8 9;...
        6 4 5;...
        10 11 12;...
        2 1 3;...
        8 7 9;...
        10 11 12]

then the output must be :

T_out = [1 2 3;...
         4 5 6;...
         7 8 9;...
         10 11 12]

since rows [1 2 3], [6 4 5], [2 1 3], [8 7 9], and [10 11 12] are just duplicata. Indeed triangle [i2 i1 i3] is the same as triangle [i1 i2 i3] for example.

Hypothesis :

  • T is always a N x 3 integer matrix with N > 0 (non empty matrix)
  • Each row / triangle of T always contains three distinct integers

Good work Matlab bro ! :)

Solution Stats

53.77% Correct | 46.23% Incorrect
Last Solution submitted on Jun 23, 2025

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