Submission #62218

#	Time	Username	Problem	Language	Result	Execution time	Memory
62218		qkxwsm	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	779 ms	80552 KiB

commuter_pass

/*
PROG: source
LANG: C++11
    _____
  .'     '.
 /  0   0  \
|     ^     |
|  \     /  |
 \  '---'  /
  '._____.'
 */
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

struct chash
{
    int operator()(int x) const
	{
		x ^= (x >> 20) ^ (x >> 12);
    	return x ^ (x >> 7) ^ (x >> 4);
	}
	int operator()(long long x) const
	{
		return x ^ (x >> 32);
	}
};

template<typename T> using orderedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using hashtable = gp_hash_table<T, T, chash>;

template<class T>
void readi(T &x)
{
	T input = 0;
	bool negative = false;
	char c = ' ';
	while (c < '-')
	{
		c = getchar();
	}
	if (c == '-')
	{
		negative = true;
		c = getchar();
	}
	while (c >= '0')
	{
		input = input * 10 + (c - '0');
		c = getchar();
	}
	if (negative)
	{
		input = -input;
	}
	x = input;
}
template<class T>
void printi(T output)
{
	if (output == 0)
	{
		putchar('0');
		return;
	}
	if (output < 0)
	{
		putchar('-');
		output = -output;
	}
	int aout[20];
	int ilen = 0;
	while(output)
	{
		aout[ilen] = ((output % 10));
		output /= 10;
		ilen++;
	}
	for (int i = ilen - 1; i >= 0; i--)
	{
		putchar(aout[i] + '0');
	}
	return;
}
template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
template<class T>
T normalize(T x, T mod = 1000000007)
{
	return (((x % mod) + mod) % mod);
}
long long randomizell(long long mod)
{
	return ((1ll << 45) * rand() + (1ll << 30) * rand() + (1ll << 15) * rand() + rand()) % mod;
}
int randomize(int mod)
{
	return ((1ll << 15) * rand() + rand()) % mod;
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 100013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<ld, ld> pdd;

int N, M;
int S, T, U, V;
vector<pli> edge[MAXN];
ll distS[MAXN], distT[MAXN], distU[MAXN], distV[MAXN], big;
priority_queue<pli, vector<pli>, greater<pli> > pq;
ll ans = LLINF;
ll opt[MAXN];
bool seen[MAXN];

void solve(int u, bool flag)
{
    if (seen[u])
    {
        return;
    }
    seen[u] = true;
    // cerr << "solve " << u << ' ' << flag << endl;
    for (pli p : edge[u])
    {
        ll ed = p.fi; int v = p.se;
        // cerr << u << " -> " << v << ' ' << distS[v] << ' ' << ed << ' ' << distT[u] << endl;
        if (distS[v] + ed + distT[u] == big)
        {
            solve(v, flag);
            ckmin(opt[u], opt[v]);
        }
    }
    // cerr << u << ' ' << opt[u] << endl;
    if (flag)
    {
        // cerr << u << ' ' << distU[u] <<  ' ' << opt[u] << endl;
        ckmin(ans, distU[u] + opt[u]);
    }
    else
    {
        // cerr << U << ' ' << distV[u] << ' ' << opt[u] << endl;
        ckmin(ans, distV[u] + opt[u]);
    }
    return;
}

int32_t main()
{
	ios_base::sync_with_stdio(0);
	srand(time(0));
	//	cout << fixed << setprecision(10);
	//	cerr << fixed << setprecision(10);
	if (fopen("input.in", "r"))
	{
		freopen ("input.in", "r", stdin);
		freopen ("output.out", "w", stdout);
	}
    cin >> N >> M;
    cin >> S >> T >> U >> V;
    S--; T--; U--; V--;
    for (int i = 0; i < M; i++)
    {
        int u, v; ll d;
        cin >> u >> v >> d;
        u--; v--;
        edge[u].PB(MP(d, v));
        edge[v].PB(MP(d, u));
    }
    for (int i = 0; i < N; i++)
    {
        distS[i] = LLINF; distT[i] = LLINF;
        distU[i] = LLINF; distV[i] = LLINF;
    }
    distS[S] = 0;
    pq.push(MP(0, S));
    while(!pq.empty())
    {
        ll d = pq.top().fi; int u = pq.top().se;
        pq.pop();
        if (distS[u] != d)
        {
            continue;
        }
        for (pli p : edge[u])
        {
            ll ed = p.fi; int v = p.se;
            if (distS[v] > d + ed)
            {
                distS[v] = d + ed;
                pq.push({distS[v], v});
            }
        }
    }
    distT[T] = 0;
    pq.push(MP(0, T));
    while(!pq.empty())
    {
        ll d = pq.top().fi; int u = pq.top().se;
        pq.pop();
        if (distT[u] != d)
        {
            continue;
        }
        for (pli p : edge[u])
        {
            ll ed = p.fi; int v = p.se;
            if (distT[v] > d + ed)
            {
                distT[v] = d + ed;
                pq.push({distT[v], v});
            }
        }
    }
    distU[U] = 0;
    pq.push(MP(0, U));
    while(!pq.empty())
    {
        ll d = pq.top().fi; int u = pq.top().se;
        pq.pop();
        if (distU[u] != d)
        {
            continue;
        }
        for (pli p : edge[u])
        {
            ll ed = p.fi; int v = p.se;
            if (distU[v] > d + ed)
            {
                distU[v] = d + ed;
                pq.push({distU[v], v});
            }
        }
    }
    distV[V] = 0;
    pq.push(MP(0, V));
    while(!pq.empty())
    {
        ll d = pq.top().fi; int u = pq.top().se;
        pq.pop();
        if (distV[u] != d)
        {
            continue;
        }
        for (pli p : edge[u])
        {
            ll ed = p.fi; int v = p.se;
            if (distV[v] > d + ed)
            {
                distV[v] = d + ed;
                pq.push({distV[v], v});
            }
        }
    }
    big = distS[T];
    // cerr << "ST=UV\n";
    ans = distU[V];
    for (int i = 0; i < N; i++)
    {
        seen[i] = false;
        opt[i] = distU[i];
    }
    solve(T, 0);
    // cerr << "ST=VU\n";
    for (int i = 0; i < N; i++)
    {
        seen[i] = false;
        opt[i] = distV[i];
    }
    solve(T, 1);
    cout << ans << '\n';
	//	cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int32_t main()':
commuter_pass.cpp:193:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen ("input.in", "r", stdin);
   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:194:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen ("output.out", "w", stdout);
   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45