133-CloneGraph.go

package main

// 133. Clone Graph
// Given a reference of a node in a connected undirected graph.
// Return a deep copy (clone) of the graph.
// Each node in the graph contains a value (int) and a list (List[Node]) of its neighbors.
//     class Node {
//         public int val;
//         public List<Node> neighbors;
//     }

// Test case format:
//     For simplicity, each node's value is the same as the node's index (1-indexed). 
//     For example, the first node with val == 1, the second node with val == 2, and so on. 
//     The graph is represented in the test case using an adjacency list.

//     An adjacency list is a collection of unordered lists used to represent a finite graph. 
//     Each list describes the set of neighbors of a node in the graph.

//     The given node will always be the first node with val = 1. 
//     You must return the copy of the given node as a reference to the cloned graph.

// Example 1:
// <img src="https://assets.leetcode.com/uploads/2019/11/04/133_clone_graph_question.png" />
// Input: adjList = [[2,4],[1,3],[2,4],[1,3]]
// Output: [[2,4],[1,3],[2,4],[1,3]]
// Explanation: There are 4 nodes in the graph.
// 1st node (val = 1)'s neighbors are 2nd node (val = 2) and 4th node (val = 4).
// 2nd node (val = 2)'s neighbors are 1st node (val = 1) and 3rd node (val = 3).
// 3rd node (val = 3)'s neighbors are 2nd node (val = 2) and 4th node (val = 4).
// 4th node (val = 4)'s neighbors are 1st node (val = 1) and 3rd node (val = 3).

// Example 2:
// <img src="https://assets.leetcode.com/uploads/2020/01/07/graph.png" />
// Input: adjList = [[]]
// Output: [[]]
// Explanation: Note that the input contains one empty list. The graph consists of only one node with val = 1 and it does not have any neighbors.

// Example 3:
// Input: adjList = []
// Output: []
// Explanation: This an empty graph, it does not have any nodes.

// Constraints:
//     The number of nodes in the graph is in the range [0, 100].
//     1 <= Node.val <= 100
//     Node.val is unique for each node.
//     There are no repeated edges and no self-loops in the graph.
//     The Graph is connected and all nodes can be visited starting from the given node.

import "fmt"

type Node struct {
    Val int
    Neighbors []*Node
}

/**
 * Definition for a Node.
 * type Node struct {
 *     Val int
 *     Neighbors []*Node
 * }
 */
// dfs
func cloneGraph(node *Node) *Node {
    if node == nil {
        return nil
    }
    copies := make([]*Node, 101)
    var dfs func (node *Node, copies []*Node) 
    dfs = func (node *Node, copies []*Node) {
        newNode := new(Node)
        newNode.Val = node.Val
        copies[node.Val] = newNode
        for _, neighbor := range node.Neighbors {
            if copies[neighbor.Val] == nil {
                dfs(neighbor, copies)
            }
            newNode.Neighbors = append(newNode.Neighbors, copies[neighbor.Val])
        }
    }
    dfs(node, copies)
    return copies[node.Val]
}

func main() {
    fmt.Println(111)
}