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Add solution and test-cases for problem 834

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leetcode/801-900/0834.Sum-of-Distances-in-Tree

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`‎leetcode/801-900/0834.Sum-of-Distances-in-Tree/README.md‎`

Lines changed: 27 additions & 13 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,28 +1,42 @@`
`1`	`1`	`# [834.Sum of Distances in Tree][title]`
`2`	`2`
`3`		`-> [!WARNING\|style:flat]`
`4`		`-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)`
`5`		`-`
`6`	`3`	`## Description`
	`4`	+There is an undirected connected tree with n nodes labeled from `0` to `n - 1` and `n - 1` edges.
	`5`	`+`
	`6`	+You are given the integer `n` and the array `edges` where `edges[i] = [ai, bi]` indicates that there is an edge between nodes a<sub>i</sub> and b<sub>i</sub> in the tree.
	`7`	`+`
	`8`	+Return an array `answer` of length `n` where `answer[i]` is the sum of the distances between the i<sup>th</sup> node in the tree and all other nodes.
`7`	`9`
`8`		`-Example 1:`
	`10`	`+Example 1:`
	`11`	`+`
	`12`	`+![example1](./lc-sumdist1.jpg)`
`9`	`13`
`10`	`14`	```
`11`		`-Input: a = "11", b = "1"`
`12`		`-Output: "100"`
	`15`	`+Input: n = 6, edges = [[0,1],[0,2],[2,3],[2,4],[2,5]]`
	`16`	`+Output: [8,12,6,10,10,10]`
	`17`	`+Explanation: The tree is shown above.`
	`18`	`+We can see that dist(0,1) + dist(0,2) + dist(0,3) + dist(0,4) + dist(0,5)`
	`19`	`+equals 1 +たす 1 +たす 2 +たす 2 +たす 2 =わ 8.`
	`20`	`+Hence, answer[0] = 8, and so on.`
`13`	`21`	```
`14`	`22`
`15`		`-## 题意`
`16`		`-> ...`
	`23`	`+Example 2:`
`17`	`24`
`18`		`-## 题解`
	`25`	`+![example2](./lc-sumdist2.jpg)`
`19`	`26`
`20`		`-### 思路1`
`21`		`-> ...`
`22`		`-Sum of Distances in Tree`
`23`		-```go
	`27`	+```
	`28`	`+Input: n = 1, edges = []`
	`29`	`+Output: [0]`
`24`	`30`	```
`25`	`31`
	`32`	`+Example 3:`
	`33`	`+`
	`34`	`+![example3](./lc-sumdist3.jpg)`
	`35`	`+`
	`36`	+```
	`37`	`+Input: n = 2, edges = [[1,0]]`
	`38`	`+Output: [1,1]`
	`39`	+```
`26`	`40`
`27`	`41`	`## 结语`
`28`	`42`

`‎leetcode/801-900/0834.Sum-of-Distances-in-Tree/Solution.go‎`

Lines changed: 38 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,41 @@`
`1`	`1`	`package Solution`
`2`	`2`
`3`		`-func Solution(x bool) bool {`
`4`		`- return x`
	`3`	`+// 借鉴官方算法`
	`4`	`+func Solution(n int, edges [][]int) []int {`
	`5`	`+ adj := make(map[int]map[int]struct{})`
	`6`	`+ for u := 0; u < n; u++ {`
	`7`	`+ adj[u] = make(map[int]struct{})`
	`8`	`+ }`
	`9`	`+ for _, e := range edges {`
	`10`	`+ adj[e[0]][e[1]] = struct{}{}`
	`11`	`+ adj[e[1]][e[0]] = struct{}{}`
	`12`	`+ }`
	`13`	`+`
	`14`	`+ ans := make([]int, n)`
	`15`	`+ count := make([]int, n)`
	`16`	`+ for i := 0; i < n; i++ {`
	`17`	`+ count[i] = 1`
	`18`	`+ }`
	`19`	`+ var dfs func(int, int)`
	`20`	`+ var dfs1 func(int, int)`
	`21`	`+ dfs = func(node, parent int) {`
	`22`	`+ for child := range adj[node] {`
	`23`	`+ if child != parent {`
	`24`	`+ dfs(child, node)`
	`25`	`+ count[node] += count[child]`
	`26`	`+ ans[node] += ans[child] + count[child]`
	`27`	`+ }`
	`28`	`+ }`
	`29`	`+ }`
	`30`	`+ dfs1 = func(node, parent int) {`
	`31`	`+ for child := range adj[node] {`
	`32`	`+ if child != parent {`
	`33`	`+ ans[child] = ans[node] - count[child] + n - count[child]`
	`34`	`+ dfs1(child, node)`
	`35`	`+ }`
	`36`	`+ }`
	`37`	`+ }`
	`38`	`+ dfs(0, -1)`
	`39`	`+ dfs1(0, -1)`
	`40`	`+ return ans`
`5`	`41`	`}`

`‎leetcode/801-900/0834.Sum-of-Distances-in-Tree/Solution_test.go‎`

Lines changed: 13 additions & 10 deletions

Original file line number	Diff line number	Diff line change
`@@ -10,30 +10,33 @@ func TestSolution(t *testing.T) {`
`10`	`10`	`// 测试用例`
`11`	`11`	`cases := []struct {`
`12`	`12`	`name string`
`13`		`- inputs bool`
`14`		`- expect bool`
	`13`	`+ n int`
	`14`	`+ edges [][]int`
	`15`	`+ expect []int`
`15`	`16`	`}{`
`16`		`- {"TestCase", true, true},`
`17`		`- {"TestCase", true, true},`
`18`		`- {"TestCase", false, false},`
	`17`	`+ {"TestCase1", 6, [][]int{{0, 1}, {0, 2}, {2, 3}, {2, 4}, {2, 5}}, []int{8, 12, 6, 10, 10, 10}},`
	`18`	`+ {"TestCase2", 1, [][]int{}, []int{0}},`
	`19`	`+ {"TestCase3", 2, [][]int{{1, 0}}, []int{1, 1}},`
	`20`	`+ {"TestCase4", 4, [][]int{{2, 0}, {3, 1}, {2, 1}}, []int{6, 4, 4, 6}},`
	`21`	`+ {"TestCase5", 5, [][]int{{0, 4}, {1, 3}, {1, 2}, {0, 2}}, []int{7, 7, 6, 10, 10}},`
`19`	`22`	`}`
`20`	`23`
`21`	`24`	`// 开始测试`
`22`	`25`	`for i, c := range cases {`
`23`	`26`	`t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {`
`24`		`- got := Solution(c.inputs)`
	`27`	`+ got := Solution(c.n, c.edges)`
`25`	`28`	`if !reflect.DeepEqual(got, c.expect) {`
`26`		`- t.Fatalf("expected: %v, but got: %v, with inputs: %v",`
`27`		`- c.expect, got, c.inputs)`
	`29`	`+ t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",`
	`30`	`+ c.expect, got, c.n, c.edges)`
`28`	`31`	`}`
`29`	`32`	`})`
`30`	`33`	`}`
`31`	`34`	`}`
`32`	`35`
`33`		`-//压力测试`
	`36`	`+//压力测试`
`34`	`37`	`func BenchmarkSolution(b *testing.B) {`
`35`	`38`	`}`
`36`	`39`
`37`		`-//使用案列`
	`40`	`+//使用案列`
`38`	`41`	`func ExampleSolution() {`
`39`	`42`	`}`