[JS] Count distinct triagles

distinctTriangles.js

// Given a list of N triangles with integer side lengths, determine how many different triangles there are. 
// Two triangles are considered to be the same if they can both be placed on the plane such that their vertices
// occupy exactly the same three points.
// https://leetcode.com/discuss/interview-question/922155/facebook-recruiting-portal-counting-triangles

function sortTriangle([a, b, c]) {
  if(b > a) { 
    if(c > b) return [c, b, a];
    else if(c > a) return [b, c, a];
    else return [b, a, c];
  }
  else {
    if(c > a) return [c, a, b];
    else if(c > b) return [a, c, b];
    else return [a, b, c];
  }
}


function countDistinctTriangles(triangles) {
  const triangleGraph = {};
  let distinctTrianglesCount = 0;
  triangles.forEach(triangle => {
    const [a, b, c] = sortTriangle(triangle);
    
    let countIncrease = 0;
    if(triangleGraph[a]){
      if(triangleGraph[a][b]){
        if(!triangleGraph[a][b][c]){
          countIncrease = 1;
          triangleGraph[a][b][c] = true;
        }
      }
      else {
          countIncrease = 1;
          triangleGraph[a][b] = {};
          triangleGraph[a][b][c] = true;
      }
    }
    else {
      countIncrease = 1;
      triangleGraph[a] = {};
      triangleGraph[a][b] = {};
      triangleGraph[a][b][c] = true;
    }
    distinctTrianglesCount += countIncrease;
  });
  return distinctTrianglesCount;
}


function countDistinctTriangles(arr) {
  const ans = {};
  arr.forEach((tri) => {
    const key = tri.sort((a,b) => a > b ? 1 : -1).join("");
    if(!ans[key]) ans[key] = true;
  });
  return Object.keys(ans).length;
}
// --------------------------------------------------- Test --------------------------------------------------------//
console.log(countDistinctTriangles([[7, 6, 5], [5, 7, 6], [8, 2, 9], [2, 3, 4], [2, 4, 3]])); // 3
console.log(countDistinctTriangles([[3, 4, 5], [8, 8, 9], [7, 7, 7]])); // 3