function createGraph(nodes, edges) {
  const result = nodes.reduce((acc, el) => {
    acc[el] = [];
    return acc;
  }, {});
  for (let edge of edges) {
    result[edge[0]].push(edge[1]);
  }
  return result;
}

function dfsWithMark(graph, currentNode) {
  const visited = {};
  const marks = {};
  let step = 1;
  const pathForReverse = [];

  const inner = function (node) {
      let nextEl = graph[node].find(el => !visited[el]);
      if (nextEl !== undefined) {
          visited[nextEl] = 1;
          pathForReverse.push(node);
      } else {
          nextEl = pathForReverse.pop();
      }
      if (nextEl === undefined) return;
      marks[nextEl] = ++step;
      inner(nextEl);
  }
  
  inner(currentNode);
  return marks;
}

function reverseGraph(graph) {
    const result = nodes.reduce((acc, el) => {
        acc[el] = [];
        return acc;
      }, {})
    for (let node in graph) {
        for (let child of graph[node]) {
            if (!result[child]) {
                result[child] = [];
            }
            result[child].push(node);
        }
    }
    return result;
}

function kosaraju(nodes, edges) {
  const graph = createGraph(nodes, edges);
  const reversedGraph = reverseGraph(graph);
  
  const marks = dfsWithMark(graph, nodes[0]);
  const sortedMarks = Object.entries(marks).sort((a, b) => b[1] - a[1]);
  
  const stronglyConnectedComponents = [];
  let groupIndex = 0;
  let next = undefined;
  let visited = {};
  for (let node of sortedMarks) {
      if (visited[node[0]]) continue;
      visited[node[0]] = 1;
      stronglyConnectedComponents[groupIndex] = [node[0]];
      
      next = reversedGraph[node[0]].find(el => !visited[el]);
      if (next === undefined) {
          groupIndex++;
          continue;
      }
      while (next !== undefined) {
          visited[next] = 1;
          stronglyConnectedComponents[groupIndex].push(next);
          next = reversedGraph[next].find(el => !visited[el])
      }
      groupIndex++;
  }
  
  return stronglyConnectedComponents;
}


const nodes = [0, 1, 2, 3, 4, 5, 6, 7, 20];
const edges = [
  [0, 1],
  [1, 2],
  [1, 3],
  [3, 1],
  [3, 4],
  [4, 20],
  [4, 5],
  [5, 6],
  [6, 3],
  [6, 7],
];
const r = kosaraju(nodes, edges);
console.log(r);