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Sep 17, 2024
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feat: add solutions to lc problem: No.0815 #3531

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370 changes: 220 additions & 150 deletions solution/0800-0899/0815.Bus Routes/README.md
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373 changes: 202 additions & 171 deletions solution/0800-0899/0815.Bus Routes/README_EN.md
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68 changes: 32 additions & 36 deletions solution/0800-0899/0815.Bus Routes/Solution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4,49 +4,45 @@ class Solution {
if (source == target) {
return 0;
}
int n = routes.size();
vector<unordered_set<int>> s(n);
vector<vector<int>> g(n);
unordered_map<int, vector<int>> d;
for (int i = 0; i < n; ++i) {
for (int v : routes[i]) {
s[i].insert(v);
d[v].push_back(i);

unordered_map<int, vector<int>> g;
for (int i = 0; i < routes.size(); i++) {
for (int stop : routes[i]) {
g[stop].push_back(i);
}
}
for (auto& [_, ids] : d) {
int m = ids.size();
for (int i = 0; i < m; ++i) {
for (int j = i + 1; j < m; ++j) {
int a = ids[i], b = ids[j];
g[a].push_back(b);
g[b].push_back(a);
}
}
}
queue<int> q;
unordered_set<int> vis;
int ans = 1;
for (int v : d[source]) {
q.push(v);
vis.insert(v);

if (!g.contains(source) || !g.contains(target)) {
return -1;
}

queue<pair<int, int>> q;
unordered_set<int> visBus;
unordered_set<int> visStop;
q.push({source, 0});
visStop.insert(source);

while (!q.empty()) {
for (int k = q.size(); k; --k) {
int i = q.front();
q.pop();
if (s[i].count(target)) {
return ans;
}
for (int j : g[i]) {
if (!vis.count(j)) {
vis.insert(j);
q.push(j);
auto [stop, busCount] = q.front();
q.pop();

if (stop == target) {
return busCount;
}

for (int bus : g[stop]) {
if (!visBus.contains(bus)) {
for (int nextStop : routes[bus]) {
if (!visStop.contains(nextStop)) {
visBus.insert(bus);
visStop.insert(nextStop);
q.push({nextStop, busCount + 1});
}
}
}
}
++ans;
}

return -1;
}
};
};
56 changes: 25 additions & 31 deletions solution/0800-0899/0815.Bus Routes/Solution.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,45 +4,39 @@ public int NumBusesToDestination(int[][] routes, int source, int target) {
return 0;
}

Dictionary<int, HashSet<int>> stopToRoutes = new Dictionary<int, HashSet<int>>();
List<HashSet<int>> routeToStops = new List<HashSet<int>>();

Dictionary<int, List<int>> g = new Dictionary<int, List<int>>();
for (int i = 0; i < routes.Length; i++) {
routeToStops.Add(new HashSet<int>());
foreach (int stop in routes[i]) {
routeToStops[i].Add(stop);
if (!stopToRoutes.ContainsKey(stop)) {
stopToRoutes[stop] = new HashSet<int>();
if (!g.ContainsKey(stop)) {
g[stop] = new List<int>();
}
stopToRoutes[stop].Add(i);
g[stop].Add(i);
}
}

Queue<int> queue = new Queue<int>();
HashSet<int> visited = new HashSet<int>();
int ans = 0;

foreach (int routeId in stopToRoutes[source]) {
queue.Enqueue(routeId);
visited.Add(routeId);
if (!g.ContainsKey(source) || !g.ContainsKey(target)) {
return -1;
}

while (queue.Count > 0) {
int count = queue.Count;
ans++;

for (int i = 0; i < count; i++) {
int routeId = queue.Dequeue();

foreach (int stop in routeToStops[routeId]) {
if (stop == target) {
return ans;
}

foreach (int nextRoute in stopToRoutes[stop]) {
if (!visited.Contains(nextRoute)) {
visited.Add(nextRoute);
queue.Enqueue(nextRoute);
Queue<int[]> q = new Queue<int[]>();
HashSet<int> visBus = new HashSet<int>();
HashSet<int> visStop = new HashSet<int>();
q.Enqueue(new int[]{source, 0});
visStop.Add(source);

while (q.Count > 0) {
int[] current = q.Dequeue();
int stop = current[0], busCount = current[1];
if (stop == target) {
return busCount;
}
foreach (int bus in g[stop]) {
if (!visBus.Contains(bus)) {
foreach (int nextStop in routes[bus]) {
if (!visStop.Contains(nextStop)) {
visBus.Add(bus);
visStop.Add(nextStop);
q.Enqueue(new int[]{nextStop, busCount + 1});
}
}
}
Expand Down
73 changes: 34 additions & 39 deletions solution/0800-0899/0815.Bus Routes/Solution.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,50 +2,45 @@ func numBusesToDestination(routes [][]int, source int, target int) int {
if source == target {
return 0
}
n := len(routes)
s := make([]map[int]bool, n)
g := make([][]int, n)
d := map[int][]int{}
for i, r := range routes {
for _, v := range r {
if s[i] == nil {
s[i] = make(map[int]bool)
}
s[i][v] = true
d[v] = append(d[v], i)
}
}
for _, ids := range d {
m := len(ids)
for i := 0; i < m; i++ {
for j := i + 1; j < m; j++ {
a, b := ids[i], ids[j]
g[a] = append(g[a], b)
g[b] = append(g[b], a)
}

g := make(map[int][]int)
for i, route := range routes {
for _, stop := range route {
g[stop] = append(g[stop], i)
}
}
q := d[source]
vis := map[int]bool{}
for _, v := range d[source] {
vis[v] = true

if g[source] == nil || g[target] == nil {
return -1
}
ans := 1
for len(q) > 0 {
for k := len(q); k > 0; k-- {
i := q[0]
q = q[1:]
if s[i][target] {
return ans
}
for _, j := range g[i] {
if !vis[j] {
vis[j] = true
q = append(q, j)

q := list.New()
q.PushBack([2]int{source, 0})
visBus := make(map[int]bool)
visStop := make(map[int]bool)
visStop[source] = true

for q.Len() > 0 {
front := q.Front()
q.Remove(front)
stop, busCount := front.Value.([2]int)[0], front.Value.([2]int)[1]

if stop == target {
return busCount
}

for _, bus := range g[stop] {
if !visBus[bus] {
visBus[bus] = true
for _, nextStop := range routes[bus] {
if !visStop[nextStop] {
visStop[nextStop] = true
q.PushBack([2]int{nextStop, busCount + 1})
}
}
}
}
ans++
}

return -1
}
}
66 changes: 29 additions & 37 deletions solution/0800-0899/0815.Bus Routes/Solution.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,50 +3,42 @@ public int numBusesToDestination(int[][] routes, int source, int target) {
if (source == target) {
return 0;
}
int n = routes.length;
Set<Integer>[] s = new Set[n];
List<Integer>[] g = new List[n];
Arrays.setAll(s, k -> new HashSet<>());
Arrays.setAll(g, k -> new ArrayList<>());
Map<Integer, List<Integer>> d = new HashMap<>();
for (int i = 0; i < n; ++i) {
for (int v : routes[i]) {
s[i].add(v);
d.computeIfAbsent(v, k -> new ArrayList<>()).add(i);

Map<Integer, List<Integer>> g = new HashMap<>();
for (int i = 0; i < routes.length; i++) {
for (int stop : routes[i]) {
g.computeIfAbsent(stop, k -> new ArrayList<>()).add(i);
}
}
for (var ids : d.values()) {
int m = ids.size();
for (int i = 0; i < m; ++i) {
for (int j = i + 1; j < m; ++j) {
int a = ids.get(i), b = ids.get(j);
g[a].add(b);
g[b].add(a);
}
}
}
Deque<Integer> q = new ArrayDeque<>();
Set<Integer> vis = new HashSet<>();
int ans = 1;
for (int v : d.get(source)) {
q.offer(v);
vis.add(v);

if (!g.containsKey(source) || !g.containsKey(target)) {
return -1;
}

Deque<int[]> q = new ArrayDeque<>();
Set<Integer> visBus = new HashSet<>();
Set<Integer> visStop = new HashSet<>();
q.offer(new int[] {source, 0});
visStop.add(source);

while (!q.isEmpty()) {
for (int k = q.size(); k > 0; --k) {
int i = q.pollFirst();
if (s[i].contains(target)) {
return ans;
}
for (int j : g[i]) {
if (!vis.contains(j)) {
vis.add(j);
q.offer(j);
int[] current = q.poll();
int stop = current[0], busCount = current[1];

if (stop == target) {
return busCount;
}
for (int bus : g.get(stop)) {
if (visBus.add(bus)) {
for (int nextStop : routes[bus]) {
if (visStop.add(nextStop)) {
q.offer(new int[] {nextStop, busCount + 1});
}
}
}
}
++ans;
}

return -1;
}
}
}
48 changes: 18 additions & 30 deletions solution/0800-0899/0815.Bus Routes/Solution.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,35 +4,23 @@ def numBusesToDestination(
) -> int:
if source == target:
return 0

# 一条公交线路有哪些公交站
s = [set(r) for r in routes]

# 一个公交站在哪些公交线路有
d = defaultdict(list)
for i, r in enumerate(routes):
for v in r:
d[v].append(i)

g = defaultdict(list)
for ids in d.values():
m = len(ids)
for i in range(m):
for j in range(i + 1, m):
a, b = ids[i], ids[j]
g[a].append(b)
g[b].append(a)
q = deque(d[source])
ans = 1
vis = set(d[source])
while q:
for _ in range(len(q)):
i = q.popleft()
if target in s[i]:
return ans
for j in g[i]:
if j not in vis:
vis.add(j)
q.append(j)
ans += 1
for i, route in enumerate(routes):
for stop in route:
g[stop].append(i)
if source not in g or target not in g:
return -1
q = [(source, 0)]
vis_bus = set()
vis_stop = {source}
for stop, bus_count in q:
if stop == target:
return bus_count
for bus in g[stop]:
if bus not in vis_bus:
vis_bus.add(bus)
for next_stop in routes[bus]:
if next_stop not in vis_stop:
vis_stop.add(next_stop)
q.append((next_stop, bus_count + 1))
return -1
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