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Oct 28, 2024
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feat: update lc problems #3679

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721 changes: 610 additions & 111 deletions solution/0600-0699/0685.Redundant Connection II/README.md
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723 changes: 613 additions & 110 deletions solution/0600-0699/0685.Redundant Connection II/README_EN.md
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75 changes: 35 additions & 40 deletions solution/0600-0699/0685.Redundant Connection II/Solution.cpp
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Original file line number Diff line number Diff line change
@@ -1,48 +1,43 @@
class UnionFind {
public:
vector<int> p;
int n;

UnionFind(int _n)
: n(_n)
, p(_n) {
iota(p.begin(), p.end(), 0);
}

bool unite(int a, int b) {
int pa = find(a), pb = find(b);
if (pa == pb) return false;
p[pa] = pb;
--n;
return true;
}

int find(int x) {
if (p[x] != x) p[x] = find(p[x]);
return p[x];
}
};

class Solution {
public:
vector<int> findRedundantDirectedConnection(vector<vector<int>>& edges) {
int n = edges.size();
vector<int> p(n + 1);
for (int i = 0; i <= n; ++i) p[i] = i;
UnionFind uf(n + 1);
int conflict = -1, cycle = -1;
vector<int> ind(n);
for (const auto& e : edges) {
++ind[e[1] - 1];
}
vector<int> dup;
for (int i = 0; i < n; ++i) {
int u = edges[i][0], v = edges[i][1];
if (p[v] != v)
conflict = i;
else {
p[v] = u;
if (!uf.unite(u, v)) cycle = i;
if (ind[edges[i][1] - 1] == 2) {
dup.push_back(i);
}
}
if (conflict == -1) return edges[cycle];
int v = edges[conflict][1];
if (cycle != -1) return {p[v], v};
return edges[conflict];
vector<int> p(n);
iota(p.begin(), p.end(), 0);
function<int(int)> find = [&](int x) {
return x == p[x] ? x : p[x] = find(p[x]);
};
if (!dup.empty()) {
for (int i = 0; i < n; ++i) {
if (i == dup[1]) {
continue;
}
int pu = find(edges[i][0] - 1);
int pv = find(edges[i][1] - 1);
if (pu == pv) {
return edges[dup[0]];
}
p[pu] = pv;
}
return edges[dup[1]];
}
for (int i = 0;; ++i) {
int pu = find(edges[i][0] - 1);
int pv = find(edges[i][1] - 1);
if (pu == pv) {
return edges[i];
}
p[pu] = pv;
}
}
};
};
84 changes: 36 additions & 48 deletions solution/0600-0699/0685.Redundant Connection II/Solution.go
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Original file line number Diff line number Diff line change
@@ -1,57 +1,45 @@
type unionFind struct {
p []int
n int
}

func newUnionFind(n int) *unionFind {
p := make([]int, n)
for i := range p {
p[i] = i
}
return &unionFind{p, n}
}

func (uf *unionFind) find(x int) int {
if uf.p[x] != x {
uf.p[x] = uf.find(uf.p[x])
}
return uf.p[x]
}

func (uf *unionFind) union(a, b int) bool {
if uf.find(a) == uf.find(b) {
return false
}
uf.p[uf.find(a)] = uf.find(b)
uf.n--
return true
}

func findRedundantDirectedConnection(edges [][]int) []int {
n := len(edges)
p := make([]int, n+1)
ind := make([]int, n)
for _, e := range edges {
ind[e[1]-1]++
}
dup := []int{}
for i, e := range edges {
if ind[e[1]-1] == 2 {
dup = append(dup, i)
}
}
p := make([]int, n)
for i := range p {
p[i] = i
}
uf := newUnionFind(n + 1)
conflict, cycle := -1, -1
for i, e := range edges {
u, v := e[0], e[1]
if p[v] != v {
conflict = i
} else {
p[v] = u
if !uf.union(u, v) {
cycle = i
}
var find func(int) int
find = func(x int) int {
if p[x] != x {
p[x] = find(p[x])
}
return p[x]
}
if conflict == -1 {
return edges[cycle]
if len(dup) > 0 {
for i, e := range edges {
if i == dup[1] {
continue
}
pu, pv := find(e[0]-1), find(e[1]-1)
if pu == pv {
return edges[dup[0]]
}
p[pu] = pv
}
return edges[dup[1]]
}
v := edges[conflict][1]
if cycle != -1 {
return []int{p[v], v}
for _, e := range edges {
pu, pv := find(e[0]-1), find(e[1]-1)
if pu == pv {
return e
}
p[pu] = pv
}
return edges[conflict]
}
return nil
}
77 changes: 32 additions & 45 deletions solution/0600-0699/0685.Redundant Connection II/Solution.java
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Original file line number Diff line number Diff line change
@@ -1,61 +1,48 @@
class Solution {
private int[] p;

public int[] findRedundantDirectedConnection(int[][] edges) {
int n = edges.length;
int[] p = new int[n + 1];
for (int i = 0; i <= n; ++i) {
p[i] = i;
}
UnionFind uf = new UnionFind(n + 1);
int conflict = -1, cycle = -1;
for (int i = 0; i < n; ++i) {
int u = edges[i][0], v = edges[i][1];
if (p[v] != v) {
conflict = i;
} else {
p[v] = u;
if (!uf.union(u, v)) {
cycle = i;
}
}
int[] ind = new int[n];
for (var e : edges) {
++ind[e[1] - 1];
}
if (conflict == -1) {
return edges[cycle];
}
int v = edges[conflict][1];
if (cycle != -1) {
return new int[] {p[v], v};
}
return edges[conflict];
}
}

class UnionFind {
public int[] p;
public int n;

public UnionFind(int n) {
List<Integer> dup = new ArrayList<>();
p = new int[n];
for (int i = 0; i < n; ++i) {
if (ind[edges[i][1] - 1] == 2) {
dup.add(i);
}
p[i] = i;
}
this.n = n;
}

public boolean union(int a, int b) {
int pa = find(a);
int pb = find(b);
if (pa == pb) {
return false;
if (!dup.isEmpty()) {
for (int i = 0; i < n; ++i) {
if (i == dup.get(1)) {
continue;
}
int pu = find(edges[i][0] - 1);
int pv = find(edges[i][1] - 1);
if (pu == pv) {
return edges[dup.get(0)];
}
p[pu] = pv;
}
return edges[dup.get(1)];
}
for (int i = 0;; ++i) {
int pu = find(edges[i][0] - 1);
int pv = find(edges[i][1] - 1);
if (pu == pv) {
return edges[i];
}
p[pu] = pv;
}
p[pa] = pb;
--n;
return true;
}

public int find(int x) {
private int find(int x) {
if (p[x] != x) {
p[x] = find(p[x]);
}
return p[x];
}
}
}
44 changes: 44 additions & 0 deletions solution/0600-0699/0685.Redundant Connection II/Solution.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
/**
* @param {number[][]} edges
* @return {number[]}
*/
var findRedundantDirectedConnection = function (edges) {
const n = edges.length;
const ind = Array(n).fill(0);
for (const [_, v] of edges) {
++ind[v - 1];
}
const dup = [];
for (let i = 0; i < n; ++i) {
if (ind[edges[i][1] - 1] === 2) {
dup.push(i);
}
}
const p = Array.from({ length: n }, (_, i) => i);
const find = x => {
if (p[x] !== x) {
p[x] = find(p[x]);
}
return p[x];
};
if (dup.length) {
for (let i = 0; i < n; ++i) {
if (i === dup[1]) {
continue;
}
const [pu, pv] = [find(edges[i][0] - 1), find(edges[i][1] - 1)];
if (pu === pv) {
return edges[dup[0]];
}
p[pu] = pv;
}
return edges[dup[1]];
}
for (let i = 0; ; ++i) {
const [pu, pv] = [find(edges[i][0] - 1), find(edges[i][1] - 1)];
if (pu === pv) {
return edges[i];
}
p[pu] = pv;
}
};
56 changes: 23 additions & 33 deletions solution/0600-0699/0685.Redundant Connection II/Solution.py
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Original file line number Diff line number Diff line change
@@ -1,37 +1,27 @@
class UnionFind:
def __init__(self, n):
self.p = list(range(n))
self.n = n

def union(self, a, b):
if self.find(a) == self.find(b):
return False
self.p[self.find(a)] = self.find(b)
self.n -= 1
return True

def find(self, x):
if self.p[x] != x:
self.p[x] = self.find(self.p[x])
return self.p[x]


class Solution:
def findRedundantDirectedConnection(self, edges: List[List[int]]) -> List[int]:
def find(x: int) -> int:
if p[x] != x:
p[x] = find(p[x])
return p[x]

n = len(edges)
p = list(range(n + 1))
uf = UnionFind(n + 1)
conflict = cycle = None
ind = [0] * n
for _, v in edges:
ind[v - 1] += 1
dup = [i for i, (_, v) in enumerate(edges) if ind[v - 1] == 2]
p = list(range(n))
if dup:
for i, (u, v) in enumerate(edges):
if i == dup[1]:
continue
pu, pv = find(u - 1), find(v - 1)
if pu == pv:
return edges[dup[0]]
p[pu] = pv
return edges[dup[1]]
for i, (u, v) in enumerate(edges):
if p[v] != v:
conflict = i
else:
p[v] = u
if not uf.union(u, v):
cycle = i
if conflict is None:
return edges[cycle]
v = edges[conflict][1]
if cycle is not None:
return [p[v], v]
return edges[conflict]
pu, pv = find(u - 1), find(v - 1)
if pu == pv:
return edges[i]
p[pu] = pv
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