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feat: add solutions to lc problem: No.0684 (#3675)
No.0684.Redundant Connection
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-136
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‎solution/0600-0699/0684.Redundant Connection/README.md

+363-43
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‎solution/0600-0699/0684.Redundant Connection/README_EN.md

+363-43
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‎solution/0600-0699/0684.Redundant Connection/Solution.cpp

+14-15
Original file line numberDiff line numberDiff line change
@@ -1,20 +1,19 @@
11
class Solution {
22
public:
3-
vector<int> p;
4-
53
vector<int> findRedundantConnection(vector<vector<int>>& edges) {
6-
p.resize(1010);
7-
for (int i = 0; i < p.size(); ++i) p[i] = i;
8-
for (auto& e : edges) {
9-
int a = e[0], b = e[1];
10-
if (find(a) == find(b)) return e;
11-
p[find(a)] = find(b);
4+
int n = edges.size();
5+
vector<int> p(n);
6+
iota(p.begin(), p.end(), 0);
7+
function<int(int)> find = [&](int x) {
8+
return x == p[x] ? x : p[x] = find(p[x]);
9+
};
10+
for (int i = 0;; ++i) {
11+
int pa = find(edges[i][0] - 1);
12+
int pb = find(edges[i][1] - 1);
13+
if (pa == pb) {
14+
return edges[i];
15+
}
16+
p[pa] = pb;
1217
}
13-
return {};
1418
}
15-
16-
int find(int x) {
17-
if (p[x] != x) p[x] = find(p[x]);
18-
return p[x];
19-
}
20-
};
19+
};

‎solution/0600-0699/0684.Redundant Connection/Solution.go

+9-9
Original file line numberDiff line numberDiff line change
@@ -1,21 +1,21 @@
11
func findRedundantConnection(edges [][]int) []int {
2-
p := make([]int, 1010)
2+
n := len(edges)
3+
p := make([]int, n)
34
for i := range p {
45
p[i] = i
56
}
6-
var find func(x int) int
7+
var find func(int) int
78
find = func(x int) int {
89
if p[x] != x {
910
p[x] = find(p[x])
1011
}
1112
return p[x]
1213
}
13-
for _, e := range edges {
14-
a, b := e[0], e[1]
15-
if find(a) == find(b) {
16-
return e
14+
for i := 0; ; i++ {
15+
pa, pb := find(edges[i][0]-1), find(edges[i][1]-1)
16+
if pa == pb {
17+
return edges[i]
1718
}
18-
p[find(a)] = find(b)
19+
p[pa] = pb
1920
}
20-
return []int{}
21-
}
21+
}

‎solution/0600-0699/0684.Redundant Connection/Solution.java

+10-9
Original file line numberDiff line numberDiff line change
@@ -2,18 +2,19 @@ class Solution {
22
private int[] p;
33

44
public int[] findRedundantConnection(int[][] edges) {
5-
p = new int[1010];
6-
for (int i = 0; i < p.length; ++i) {
5+
int n = edges.length;
6+
p = new int[n];
7+
for (int i = 0; i < n; ++i) {
78
p[i] = i;
89
}
9-
for (int[] e : edges) {
10-
int a = e[0], b = e[1];
11-
if (find(a) == find(b)) {
12-
return e;
10+
for (int i = 0;; ++i) {
11+
int pa = find(edges[i][0] - 1);
12+
int pb = find(edges[i][1] - 1);
13+
if (pa == pb) {
14+
return edges[i];
1315
}
14-
p[find(a)] = find(b);
16+
p[pa] = pb;
1517
}
16-
return null;
1718
}
1819

1920
private int find(int x) {
@@ -22,4 +23,4 @@ private int find(int x) {
2223
}
2324
return p[x];
2425
}
25-
}
26+
}

‎solution/0600-0699/0684.Redundant Connection/Solution.js

+11-9
Original file line numberDiff line numberDiff line change
@@ -3,18 +3,20 @@
33
* @return {number[]}
44
*/
55
var findRedundantConnection = function (edges) {
6-
let p = Array.from({ length: 1010 }, (_, i) => i);
7-
function find(x) {
8-
if (p[x] != x) {
6+
const n = edges.length;
7+
const p = Array.from({ length: n }, (_, i) => i);
8+
const find = x => {
9+
if (p[x] !== x) {
910
p[x] = find(p[x]);
1011
}
1112
return p[x];
12-
}
13-
for (let [a, b] of edges) {
14-
if (find(a) == find(b)) {
15-
return [a, b];
13+
};
14+
for (let i = 0; ; ++i) {
15+
const pa = find(edges[i][0] - 1);
16+
const pb = find(edges[i][1] - 1);
17+
if (pa === pb) {
18+
return edges[i];
1619
}
17-
p[find(a)] = find(b);
20+
p[pa] = pb;
1821
}
19-
return [];
2022
};

‎solution/0600-0699/0684.Redundant Connection/Solution.py

+5-5
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,13 @@
11
class Solution:
22
def findRedundantConnection(self, edges: List[List[int]]) -> List[int]:
3-
def find(x):
3+
def find(x: int) -> int:
44
if p[x] != x:
55
p[x] = find(p[x])
66
return p[x]
77

8-
p = list(range(1010))
8+
p = list(range(len(edges)))
99
for a, b in edges:
10-
if find(a) == find(b):
10+
pa, pb = find(a - 1), find(b - 1)
11+
if pa == pb:
1112
return [a, b]
12-
p[find(a)] = find(b)
13-
return []
13+
p[pa] = pb

‎solution/0600-0699/0684.Redundant Connection/Solution.ts

+18
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
function findRedundantConnection(edges: number[][]): number[] {
2+
const n = edges.length;
3+
const p: number[] = Array.from({ length: n }, (_, i) => i);
4+
const find = (x: number): number => {
5+
if (p[x] !== x) {
6+
p[x] = find(p[x]);
7+
}
8+
return p[x];
9+
};
10+
for (let i = 0; ; ++i) {
11+
const pa = find(edges[i][0] - 1);
12+
const pb = find(edges[i][1] - 1);
13+
if (pa === pb) {
14+
return edges[i];
15+
}
16+
p[pa] = pb;
17+
}
18+
}

‎solution/0600-0699/0684.Redundant Connection/Solution2.cpp

+45
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
1+
class UnionFind {
2+
public:
3+
UnionFind(int n) {
4+
p = vector<int>(n);
5+
size = vector<int>(n, 1);
6+
iota(p.begin(), p.end(), 0);
7+
}
8+
9+
bool unite(int a, int b) {
10+
int pa = find(a), pb = find(b);
11+
if (pa == pb) {
12+
return false;
13+
}
14+
if (size[pa] > size[pb]) {
15+
p[pb] = pa;
16+
size[pa] += size[pb];
17+
} else {
18+
p[pa] = pb;
19+
size[pb] += size[pa];
20+
}
21+
return true;
22+
}
23+
24+
int find(int x) {
25+
if (p[x] != x) {
26+
p[x] = find(p[x]);
27+
}
28+
return p[x];
29+
}
30+
31+
private:
32+
vector<int> p, size;
33+
};
34+
35+
class Solution {
36+
public:
37+
vector<int> findRedundantConnection(vector<vector<int>>& edges) {
38+
UnionFind uf(edges.size());
39+
for (int i = 0;; ++i) {
40+
if (!uf.unite(edges[i][0] - 1, edges[i][1] - 1)) {
41+
return edges[i];
42+
}
43+
}
44+
}
45+
};

‎solution/0600-0699/0684.Redundant Connection/Solution2.go

+44
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,44 @@
1+
type unionFind struct {
2+
p, size []int
3+
}
4+
5+
func newUnionFind(n int) *unionFind {
6+
p := make([]int, n)
7+
size := make([]int, n)
8+
for i := range p {
9+
p[i] = i
10+
size[i] = 1
11+
}
12+
return &unionFind{p, size}
13+
}
14+
15+
func (uf *unionFind) find(x int) int {
16+
if uf.p[x] != x {
17+
uf.p[x] = uf.find(uf.p[x])
18+
}
19+
return uf.p[x]
20+
}
21+
22+
func (uf *unionFind) union(a, b int) bool {
23+
pa, pb := uf.find(a), uf.find(b)
24+
if pa == pb {
25+
return false
26+
}
27+
if uf.size[pa] > uf.size[pb] {
28+
uf.p[pb] = pa
29+
uf.size[pa] += uf.size[pb]
30+
} else {
31+
uf.p[pa] = pb
32+
uf.size[pb] += uf.size[pa]
33+
}
34+
return true
35+
}
36+
37+
func findRedundantConnection(edges [][]int) []int {
38+
uf := newUnionFind(len(edges))
39+
for i := 0; ; i++ {
40+
if !uf.union(edges[i][0]-1, edges[i][1]-1) {
41+
return edges[i]
42+
}
43+
}
44+
}

‎solution/0600-0699/0684.Redundant Connection/Solution2.java

+46
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
1+
class UnionFind {
2+
private final int[] p;
3+
private final int[] size;
4+
5+
public UnionFind(int n) {
6+
p = new int[n];
7+
size = new int[n];
8+
for (int i = 0; i < n; ++i) {
9+
p[i] = i;
10+
size[i] = 1;
11+
}
12+
}
13+
14+
public int find(int x) {
15+
if (p[x] != x) {
16+
p[x] = find(p[x]);
17+
}
18+
return p[x];
19+
}
20+
21+
public boolean union(int a, int b) {
22+
int pa = find(a), pb = find(b);
23+
if (pa == pb) {
24+
return false;
25+
}
26+
if (size[pa] > size[pb]) {
27+
p[pb] = pa;
28+
size[pa] += size[pb];
29+
} else {
30+
p[pa] = pb;
31+
size[pb] += size[pa];
32+
}
33+
return true;
34+
}
35+
}
36+
37+
class Solution {
38+
public int[] findRedundantConnection(int[][] edges) {
39+
UnionFind uf = new UnionFind(edges.length);
40+
for (int i = 0;; ++i) {
41+
if (!uf.union(edges[i][0] - 1, edges[i][1] - 1)) {
42+
return edges[i];
43+
}
44+
}
45+
}
46+
}

‎solution/0600-0699/0684.Redundant Connection/Solution2.js

+42
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
1+
class UnionFind {
2+
constructor(n) {
3+
this.p = Array.from({ length: n }, (_, i) => i);
4+
this.size = Array(n).fill(1);
5+
}
6+
7+
find(x) {
8+
if (this.p[x] !== x) {
9+
this.p[x] = this.find(this.p[x]);
10+
}
11+
return this.p[x];
12+
}
13+
14+
union(a, b) {
15+
const pa = this.find(a);
16+
const pb = this.find(b);
17+
if (pa === pb) {
18+
return false;
19+
}
20+
if (this.size[pa] > this.size[pb]) {
21+
this.p[pb] = pa;
22+
this.size[pa] += this.size[pb];
23+
} else {
24+
this.p[pa] = pb;
25+
this.size[pb] += this.size[pa];
26+
}
27+
return true;
28+
}
29+
}
30+
31+
/**
32+
* @param {number[][]} edges
33+
* @return {number[]}
34+
*/
35+
var findRedundantConnection = function (edges) {
36+
const uf = new UnionFind(edges.length);
37+
for (let i = 0; i < edges.length; i++) {
38+
if (!uf.union(edges[i][0] - 1, edges[i][1] - 1)) {
39+
return edges[i];
40+
}
41+
}
42+
};

‎solution/0600-0699/0684.Redundant Connection/Solution2.py

+31
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
1+
class UnionFind:
2+
__slots__ = "p", "size"
3+
4+
def __init__(self, n: int):
5+
self.p: List[int] = list(range(n))
6+
self.size: List[int] = [1] * n
7+
8+
def find(self, x: int) -> int:
9+
if self.p[x] != x:
10+
self.p[x] = self.find(self.p[x])
11+
return self.p[x]
12+
13+
def union(self, a: int, b: int) -> bool:
14+
pa, pb = self.find(a), self.find(b)
15+
if pa == pb:
16+
return False
17+
if self.size[pa] > self.size[pb]:
18+
self.p[pb] = pa
19+
self.size[pa] += self.size[pb]
20+
else:
21+
self.p[pa] = pb
22+
self.size[pb] += self.size[pa]
23+
return True
24+
25+
26+
class Solution:
27+
def findRedundantConnection(self, edges: List[List[int]]) -> List[int]:
28+
uf = UnionFind(len(edges))
29+
for a, b in edges:
30+
if not uf.union(a - 1, b - 1):
31+
return [a, b]

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