Code to test if a graph contains triangles. Requires N^3 time :(

cubic Graph triangles

console.clear();

var g = [];

// Adjacency list representation of a graph
g[0] = [1, 3];
g[1] = [0, 2];
g[2] = [1, 3, 4];
g[3] = [0, 2, 4];
g[4] = [2, 3];


for(var i = 0; i < g.length; ++i) {
  
  var v = g[i];
  var c = 0;
  
  var connected = []
  
  console.log(i + " connects to " + v.join())
  
  for(var j = 0; j < v.length; ++j) {
    
    console.log("  " + v[j] + " connects to " + g[v[j]].join());
    
    for(var k = 0; k < g[v[j]].length; ++k) {
      
      if(g[v[j]][k] == i) {
         ++c;
        
          console.log("    has " + g[v[j]][k])
      
          connected.push(v[j])
      }
      
    }    
  }

  
  console.log("sub search: " + connected.join())

  
  var cc = 0;
  
  for(var x = 0; x < connected.length; ++x) {
    for(var y = x+1; y < connected.length; ++y) {

      console.log(" test if " + connected[x] + " in " + g[connected[y]].join())

      
      for(var k = 0; k < g[connected[y]].length; ++k) {
        
        if(g[y][k] == connected[x]) {
          cc++;
        }
      }
    }
  }
  
  
  if(c >= 2 && cc >= 2) {
    console.log("ja!");
    break;
  } else {
    console.log("nein");
  }
}