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Commit cae48e7

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Merge pull request #380 from 0xff-dev/1971
Add solution and test-cases for problem 1971
2 parents b359bda + acc2b3a commit cae48e7

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5 files changed

+120
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‎leetcode/1901-2000/1971.Find-if-Path-Exists-in-Graph/README.md‎

Lines changed: 19 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,28 +1,33 @@
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# [1971.Find if Path Exists in Graph][title]
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> [!WARNING|style:flat]
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> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
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## Description
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There is a **bi-directional** graph with `n` vertices, where each vertex is labeled from `0` to `n - 1` (**inclusive**). The edges in the graph are represented as a 2D integer array `edges`, where each `edges[i] = [ui, vi]` denotes a bi-directional edge between vertex u<sub>i</sub> and vertex v<sub>i</sub>. Every vertex pair is connected by **at most one** edge, and no vertex has an edge to itself.
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You want to determine if there is a **valid path** that exists from vertex `source` to vertex `destination`.
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Given `edges` and the integers `n`, `source`, and `destination`, return `true` if there is a **valid path** from `source` to `destination`, or `false` otherwise.
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**Example 1:**
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**Example 1:**
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![example1](./validpath-ex1.png)
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```
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Input: a = "11", b = "1"
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Output: "100"
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Input: n = 3, edges = [[0,1],[1,2],[2,0]], source = 0, destination = 2
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Output: true
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Explanation: There are two paths from vertex 0 to vertex 2:
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- 0 → 1 → 2
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- 0 → 2
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```
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## 题意
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> ...
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**Example 2:**
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## 题解
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![example2](./validpath-ex2.png)
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### 思路1
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> ...
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Find if Path Exists in Graph
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```go
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```
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Input: n = 6, edges = [[0,1],[0,2],[3,5],[5,4],[4,3]], source = 0, destination = 5
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Output: false
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Explanation: There is no path from vertex 0 to vertex 5.
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```
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## 结语
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Lines changed: 78 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,81 @@
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package Solution
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3-
func Solution(x bool) bool {
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return x
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func Solution(n int, edges [][]int, source int, destination int) bool {
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graph := make(map[int]map[int]struct{})
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for _, e := range edges {
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if _, ok := graph[e[0]]; !ok {
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graph[e[0]] = make(map[int]struct{})
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}
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if _, ok := graph[e[1]]; !ok {
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graph[e[1]] = make(map[int]struct{})
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}
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graph[e[0]][e[1]] = struct{}{}
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graph[e[1]][e[0]] = struct{}{}
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}
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visited := map[int]struct{}{}
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visited[source] = struct{}{}
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found := false
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var dfs func(int, *bool)
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dfs = func(source int, found *bool) {
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if *found {
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return
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}
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for rel := range graph[source] {
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if _, ok := visited[rel]; ok {
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continue
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}
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if rel == destination {
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*found = true
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return
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}
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visited[rel] = struct{}{}
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dfs(rel, found)
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delete(visited, rel)
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}
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}
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dfs(source, &found)
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return found
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}
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func Solution1(n int, edges [][]int, source int, destination int) bool {
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if source == destination {
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return true
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}
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graph := make(map[int]map[int]struct{})
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for _, e := range edges {
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if _, ok := graph[e[0]]; !ok {
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graph[e[0]] = make(map[int]struct{})
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}
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if _, ok := graph[e[1]]; !ok {
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graph[e[1]] = make(map[int]struct{})
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}
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graph[e[0]][e[1]] = struct{}{}
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graph[e[1]][e[0]] = struct{}{}
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}
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queue := []int{source}
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visited := map[int]struct{}{}
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visited[source] = struct{}{}
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for len(queue) > 0 {
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nq := make([]int, 0)
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for _, item := range queue {
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for rel := range graph[item] {
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if rel == destination {
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return true
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}
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if _, ok := visited[rel]; !ok {
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visited[rel] = struct{}{}
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nq = append(nq, rel)
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}
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}
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}
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queue = nq
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}
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return false
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}

‎leetcode/1901-2000/1971.Find-if-Path-Exists-in-Graph/Solution_test.go‎

Lines changed: 23 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -10,21 +10,37 @@ func TestSolution(t *testing.T) {
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// 测试用例
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cases := []struct {
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name string
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inputs bool
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n int
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edges [][]int
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source, destination int
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expect bool
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}{
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{"TestCase", true, true},
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{"TestCase", true, true},
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{"TestCase", false, false},
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{"TestCase1", 3, [][]int{
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{0, 1},
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{1, 2},
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{2, 0},
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}, 0, 2, true},
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{"TestCase2", 6, [][]int{
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{0, 1},
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{0, 2},
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{3, 5},
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{5, 4},
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{4, 3},
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}, 0, 5, false},
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}
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// 开始测试
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for i, c := range cases {
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t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
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got := Solution(c.inputs)
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got := Solution(c.n, c.edges, c.source, c.destination)
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if !reflect.DeepEqual(got, c.expect) {
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t.Fatalf("expected: %v, but got: %v, with inputs: %v",
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c.expect, got, c.inputs)
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t.Fatalf("expected: %v, but got: %v, with inputs: %v %v %v %v",
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c.expect, got, c.n, c.edges, c.source, c.destination)
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}
40+
got = Solution1(c.n, c.edges, c.source, c.destination)
41+
if !reflect.DeepEqual(got, c.expect) {
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t.Fatalf("expected: %v, but got: %v, with inputs: %v %v %v %v",
43+
c.expect, got, c.n, c.edges, c.source, c.destination)
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}
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})
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}
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