diff --git a/src/index.js b/src/index.js
index 4101a36..b60ad9b 100644
--- a/src/index.js
+++ b/src/index.js
@@ -4,7 +4,27 @@
  * @returns {number[][]}
  */
 const findNodesWithZeroAndOneParents = (parentChildPairs) => {
+  const parentsCount = {}
 
+  for (const [parent, child] of parentChildPairs) {
+    if (parentsCount[child])
+      parentsCount[child]++;
+    else
+      parentsCount[child] = 1;
+    
+    if (!parentsCount[parent]) parentsCount[parent] = 0;
+  }
+
+  const zeroParents = [], oneParent = [];
+
+  for (let node in parentsCount) {
+    node = Number(node);
+    const nodeParents = parentsCount[node];
+    if (nodeParents === 0) zeroParents.push(node);
+    else if (nodeParents === 1) oneParent.push(node);
+  }
+
+  return [zeroParents, oneParent];
 }
 
 module.exports = findNodesWithZeroAndOneParents;
\ No newline at end of file