Create 2858-minimum-edge-reversals-so-every-node-is-reachable.js

Author: everthis

2858-minimum-edge-reversals-so-every-node-is-reachable.js

@@ -0,0 +1,71 @@
+/**
+ * @param {number} n
+ * @param {number[][]} edges
+ * @return {number[]}
+ */
+const minEdgeReversals = function (n, edges) {
+  let edgesMap = {}
+  for (let i = 0; i < edges.length; i++) {
+    let a = edges[i][0]
+    let b = edges[i][1]
+    if (edgesMap[a] === undefined) {
+      edgesMap[a] = []
+    }
+    //its a forward edge
+    edgesMap[a].push([b, 'f'])
+    if (edgesMap[b] === undefined) {
+      edgesMap[b] = []
+    }
+    //its a revers edge
+    edgesMap[b].push([a, 'r'])
+  }
+
+  //We can cosnider any node as root node, Here I choose node 0
+  let res = bfs(0)
+  let ans = []
+  ans[0] = res[0]
+  let dist = res[1]
+  for (let i = 1; i < n; i++) {
+    //Ans for rest of the node will be, distance from node to root + answer of root
+    ans[i] = dist[i][0] - dist[i][1] + ans[0]
+  }
+
+  return ans
+  function bfs(root) {
+    let distance = [],
+      visited = [],
+      totalReversal = 0
+    let queue = []
+    queue.push([root, 0, 0])
+    distance[root] = [0, 0]
+    visited[root] = true
+    while (queue.length > 0) {
+      let nextLevelQueue = []
+      for (let i = 0; i < queue.length; i++) {
+        let node = queue[i][0]
+        let weightF = queue[i][1]
+        let weightR = queue[i][2]
+        for (let j = 0; j < edgesMap[node].length; j++) {
+          let neighbour = edgesMap[node][j][0]
+          if (visited[neighbour] !== undefined) {
+            continue
+          }
+          let type = edgesMap[node][j][1]
+          let f = weightF,
+            r = weightR
+          if (type === 'r') {
+            totalReversal += 1
+            r++
+          } else {
+            f++
+          }
+          visited[neighbour] = true
+          distance[neighbour] = [f, r]
+          nextLevelQueue.push([neighbour, f, r])
+        }
+      }
+      queue = nextLevelQueue
+    }
+    return [totalReversal, distance]
+  }
+}