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March 13, 2022 12:15
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/** | |
* @file dfs_bfs.cpp | |
* @author kim youngjin (youngjin.kim2@navercorp.com) | |
* @brief depth-first-search, breathe-first-search | |
* @date 2022-03-13 | |
* | |
* @copyright Copyright (c) 2022 | |
*/ | |
#include <bits/stdc++.h> | |
class Graph { | |
int n; | |
std::vector< std::vector<int> > adj; | |
void erase_duplication() { | |
for (int i = 1; i <= n; i++) | |
erase_duplication(i); | |
} | |
void erase_duplication(int u) { | |
std::vector<int> &arr = adj[u]; | |
erase_duplication(arr); | |
} | |
static void erase_duplication(std::vector<int> &arr) { | |
std::sort(arr.begin(), arr.end()); | |
arr.erase(std::unique(arr.begin(), arr.end()), arr.end()); | |
} | |
public: | |
Graph(int n, int m): n(n), adj(n+1) { | |
int s, e; | |
while (m--) { | |
scanf("%d %d", &s, &e); | |
adj[s].push_back(e); | |
adj[e].push_back(s); | |
} | |
erase_duplication(); | |
} | |
const std::vector<int>& get_adj(int u) const { | |
return adj[u]; | |
} | |
int get_n() const { return n; } | |
}; | |
class Scheduler { | |
public: | |
virtual void push(int v) = 0; | |
virtual int pop() = 0; | |
virtual bool empty() = 0; | |
}; | |
class DFSScheduler: public Scheduler { | |
std::stack<int> s; | |
public: | |
virtual void push(int v) { s.push(v); } | |
virtual int pop() { | |
int r = s.top(); | |
s.pop(); | |
return r; | |
} | |
virtual bool empty() { return s.empty(); } | |
}; | |
class BFSScheduler: public Scheduler { | |
std::queue<int> q; | |
public: | |
virtual void push(int v) { q.push(v); } | |
virtual int pop() { | |
int r = q.front(); | |
q.pop(); | |
return r; | |
} | |
virtual bool empty() { return q.empty(); } | |
}; | |
class UniqueChecker { | |
std::vector<bool> tbl; | |
public: | |
UniqueChecker(int sz): tbl(sz) {} | |
bool set(int v) { | |
bool r = tbl[v]; | |
tbl[v] = true; | |
return r; | |
} | |
void clear() { | |
std::fill(tbl.begin(), tbl.end(), false); | |
} | |
}; | |
class Traveler { | |
const Graph &g; | |
Scheduler &sched; | |
void propagate(int u) { | |
const auto a = g.get_adj(u); | |
for (auto it = a.begin(); it != a.end(); it++) { | |
sched.push(*it); | |
} | |
} | |
void propagate_reverse(int u) { | |
const auto a = g.get_adj(u); | |
for (auto it = a.rbegin(); it != a.rend(); it++) { | |
sched.push(*it); | |
} | |
} | |
public: | |
Traveler(const Graph &g, Scheduler &sched): g(g), sched(sched) {} | |
void travel(int start, std::function<void(int)> on_visit, bool reverse = false) { | |
UniqueChecker uc(g.get_n() + 1); | |
sched.push(start); | |
while (!sched.empty()) { | |
int u = sched.pop(); | |
if (uc.set(u)) | |
continue; | |
on_visit(u); | |
if (reverse) | |
propagate_reverse(u); | |
else | |
propagate(u); | |
} | |
} | |
}; | |
int main() { | |
int n, m, v; | |
scanf("%d %d %d", &n, &m, &v); | |
Graph g(n, m); | |
std::function<void(int)> on_visit = [](int v) { | |
printf("%d ", v); | |
}; | |
DFSScheduler dfs_sched; | |
Traveler dfs_traveler(g, dfs_sched); | |
dfs_traveler.travel(v, on_visit, true); | |
puts(""); | |
BFSScheduler bfs_sched; | |
Traveler bfs_traveler(g, bfs_sched); | |
bfs_traveler.travel(v, on_visit); | |
puts(""); | |
return 0; | |
} |
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