Note Book: [Light OJ] 1251 - Forming the Council

Author            : Dipu Kumar Mohanto 
                    CSE, Batch - 6
                    BRUR.
Problem Statement : 1251 - Forming the Council
Source            : Light Online Judge
Category          : Graph Theory, Strongly Connected Components, 2 SAT
Algorithm         : 2 SAT
Verdict           : Accepted

#include "bits/stdc++.h"
#include "ext/pb_ds/assoc_container.hpp"
#include "ext/pb_ds/tree_policy.hpp"
#include "ext/rope"
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define FI freopen("in.txt", "r", stdin)
#define FO freopen("out.txt", "w", stdout)
#define FAST ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define FOR(i, n) for (int i = 1; i <= n; i++)
#define For(i, n) for (int i = 0; i < n; i++)
#define ROF(i, n) for (int i = n; i >= 1; i--)
#define Rof(i, n) for (int i = n-1; i >= 0; i--)
#define FORI(i, n) for (auto i : n)
#define FORAB(i, a, b) for (int i = a; i <= b; i++)
#define ll long long
#define ull unsigned long long
#define vi vector <int>
#define vl vector <ll>
#define pii pair <int, int>
#define pll pair <ll, ll>
#define mk make_pair
#define ff first
#define ss second
#define eb emplace_back
#define em emplace
#define pb push_back
#define ppb pop_back
#define All(a) a.begin(), a.end()
#define memo(a, b) memset(a, b, sizeof a)
#define Sort(a) sort(All(a))
#define ED(a) Sort(a), a.erase(unique(All(a)), a.end())
#define rev(a) reverse(All(a))
#define sz(a) (int)a.size()
#define max3(a, b, c) max(a, max(b, c))
#define min3(a, b, c) min(a, min(b, c))
#define maxAll(a) *max_element(All(a))
#define minAll(a) *min_element(All(a))
#define allUpper(a) transform(All(a), a.begin(), :: toupper)
#define allLower(a) transform(All(a), a.begin(), :: tolower)
#define endl '\n'
#define nl puts("")
#define ub upper_bound
#define lb lower_bound
#define Exp exp(1.0)
#define PIE 2*acos(0.0)
#define Sin(a) sin(((a)*PIE)/180.0)
#define EPS 1e-9
template <typename T> using orderset = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
// rope <int> Rope;
// int dr[] = {1, -1, 0, 0}; // 4 Direction
// int dc[] = {0, 0, 1, -1};
// int dr[] = {0, 0, 1, -1, 1, 1, -1, -1}; // 8 Direction
// int dc[] = {1, -1, 0, 0, 1, -1, 1, -1};
// int dr[] = {-1, 1, -2, -2, -1, 1, 2, 2}; // knight Moves
// int dc[] = {-2, -2, -1, 1, 2, 2, 1, -1};
#define here cerr << "Here" << endl;
#define trace1(x) cerr << #x << ": " << x << endl;
#define trace2(x, y) cerr << #x << ": " << x << " | " << #y << ": " << y << endl;
#define trace3(x, y, z) cerr << #x << ": " << x << " | " << #y << ": " << y << " | " << #z << ": " << z << endl;
#define trace4(a, b, c, d) cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << endl;
#define trace5(a, b, c, d, e) cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << endl;
#define trace6(a, b, c, d, e, f) cerr << #a << ": " << a << " | " << #b << ": " << b << " | " << #c << ": " << c << " | " << #d << ": " << d << " | " << #e << ": " << e << " | " << #f << ": " << f << endl;
inline int setbit(int mask, int pos) { return mask |= (1 << pos); }
inline int resetbit(int mask, int pos) { return mask &= ~(1 << pos); }
inline int togglebit(int mask, int pos) { return mask ^= (1 << pos); }
inline bool checkbit(int mask, int pos) { return (bool)(mask & (1 << pos)); }
#define ones(mask) __builtin_popcount(mask) // count set bit
#define onesLL(mask) __builtin_popcountll(mask) // for long long
#define lzeros(mask) __builtin_clz(mask) // no of leading zeros
#define tzeros(mask) __builtin_ctz(mask) // no of trailing zeros
inline int read() { int a; scanf("%d", &a); return a; }
inline ll readLL() { ll a; scanf("%lld", &a); return a; }
inline double readDD() { double a; scanf("%lf", &a); return a; }
template <typename T> string toString(T num) { stringstream ss; ss << num; return ss.str(); }
int toInt(string s) { int num; istringstream iss(s); iss >> num; return num; }
ll toLLong(string s) { ll num; istringstream iss(s); iss >> num; return num; }
//#define inf 1e8
#define mod 1000000007
static const int maxn = 2*8000 + 5;
static const int logn = 18;
static const int inf = 1e9 + 5;
vector <int> graph[maxn], rgraph[maxn];
int finishTime[maxn], dfsTime, rfinishTime[maxn], rdfsTime;
bool vis[maxn], vis1[maxn];
int which_scc[maxn];
void dfs(int u)
{
vis[u] = 1;
for (int v : graph[u])
{
if (vis[v]) continue;
dfs(v);
}
finishTime[u] = ++dfsTime;
}
void dfs1(int u, int compo)
{
vis1[u] = 1;
which_scc[u] = compo;
for (int v : rgraph[u])
{
if (vis1[v]) continue;
dfs1(v, compo);
}
rfinishTime[u] = ++rdfsTime;
}
void clean()
{
dfsTime = 0;
rdfsTime = 0;
For(i, maxn)
{
graph[i].clear();
rgraph[i].clear();
finishTime[i] = 0;
rfinishTime[i] = 0;
which_scc[i] = 0;
vis[i] = 0;
vis1[i] = 0;
}
}
int main()
{
//FI;
int tc = read();
FOR(tcase, tc)
{
int n = read();
int m = read();
FOR(e, n)
{
int u = read();
int v = read();
if (u > 0)
{
if (v > 0)
{
graph[m+u].eb(v);
graph[m+v].eb(u);
rgraph[v].eb(m+u);
rgraph[u].eb(m+v);
}
else
{
v *= -1;
graph[m+u].eb(m+v);
graph[v].eb(u);
rgraph[m+v].eb(m+u);
rgraph[u].eb(v);
}
}
else
{
if (v > 0)
{
u *= -1;
graph[u].eb(v);
graph[m+v].eb(m+u);
rgraph[v].eb(u);
rgraph[m+u].eb(m+v);
}
else
{
u *= -1;
v *= -1;
graph[u].eb(m+v);
graph[v].eb(m+u);
rgraph[m+v].eb(u);
rgraph[m+u].eb(v);
}
}
}
FOR(i, 2*m) if (vis[i] == 0) dfs(i);
vector <pii> vec;
FOR(i, 2*m) vec.eb(finishTime[i], i);
Sort(vec);
int compo = 0;
Rof(i, sz(vec))
{
int u = vec[i].second;
if (vis1[u] == 0) dfs1(u, ++compo);
}
bool satisfiable = true;
FOR(i, m)
{
if (which_scc[i] == which_scc[m+i])
{
satisfiable = false;
break;
}
}
if (satisfiable == false)
{
printf("Case %d: No\n", tcase);
clean();
continue;
}
vi members;
FOR(i, m)
{
if (rfinishTime[i] > rfinishTime[i+m]) members.eb(i);
}
printf("Case %d: Yes\n", tcase);
printf("%d", sz(members));
For(i, sz(members)) printf(" %d", members[i]);
puts("");
clean();
}
}

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Friday, February 15, 2019

[Light OJ] 1251 - Forming the Council

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