Submission #469745

#	Time	Username	Problem	Language	Result	Execution time	Memory
469745		MohamedAliSaidane	Robot (JOI21_ho_t4)	C++14	0 / 100	373 ms	30384 KiB

Main

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> ti;
typedef unsigned long long ull;
typedef long double ld;
typedef vector<ll> vll;
typedef pair<ld,ld> pld;
#define pb push_back
#define popb pop_back()
#define pf push_front
#define popf pop_front
#define ff first
#define ss second
#define MOD (int)(1e8)
#define INF (ll) (1e18)
#define all(v) (v).begin(),(v).end()
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;}
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);}
ld pointdist(ld x, ld y, ld point) { return ((x-point)*(y-point))/abs(x-y); }
//ld dist(ld x, ld y, ld a, ld b){ return sqrt((x-a)*(x-a) + (y-b)*(y-b)); }
const int nx[8] = {0, 0, 1, -1,1,1,-1,-1}, ny[8] = {1, -1, 0, 0,1,-1,1,-1}; //East, West, South, North+
////////////******SOLUTION******\\\\\\\\\\\

const int MAX_N  = 1e5 + 4;
int n, m;
map<pii,int> ma;
vector<pii> adj[MAX_N];
int main()
{
	ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> n >> m;
    for(int i = 0; i <m; i ++)
    {
        int a, b, c, p;
        cin >> a >> b >> c >> p;
        adj[a].pb({b,c});
        adj[b].pb({a,c});
    }
    for(int i = 1; i <=n; i ++)
    {
        for(int u = 0; u < adj[i].size(); u ++)
            ma[{i,adj[i][u].ss}] ++;
    }
    set<pair<pii,int>> s;
    s.insert({{0,1},-1});
    bool visited[n+1]; memset(visited,false,sizeof(visited));
    int dist[n+1]; for(int i = 2; i <= n; i ++)dist[i] = MOD;
    while(!s.empty())
    {
        pair<pii,int> u = *(s.begin());
        s.erase(s.begin());
        int d = u.ff.ff;
        int node = u.ff.ss;
        if(visited[node]) continue;
        dist[node] = d;
        int col = u.ss;
       //cout << node << ' '  << d << ' '  << col << '\n';
        visited[node] = true;
        if(node == n)
        {
            cout << d;
            exit(0);
        }
        for(auto e: adj[node])
        {
            if(visited[e.ff]) continue;
            int occ = ma[{node,e.ss}];
            if(e.ss == col)
                occ --;
            int nvd = d + (occ > 1);
            if(dist[e.ff] > dist[node] + nvd)
            {
                dist[e.ff] = dist[node] + nvd;
                if(nvd == d)
                {
                    s.insert({{nvd,e.ff},-1});
                }
                else
                s.insert({{nvd,e.ff},e.ss});
            }
        }
    }
    cout << -1;
}
/*
Identify problem diagram: Brute force, Greedy, Dynamic Programming, Divide and Conquer
Reformulate the problem into something more theoretical
!!!!! IMPLICIT GRAPH ??????
!!!!! PAY ATTENTION TO THE CONSTRAINTS: DP nD ? BF ? BITMASKING ?
!!!!! SOLVE THE SUBTASKS FIRST: IT'S TOTALLY OK NOT TO SOLVE THE PROBLEM ENTIRELY
Search for multiple approaches: select the seemingly optimal one
Remember that you're the king of CP
Change your approach
Imagine Corner cases before submitting
Don't spend too much time on the problem: move on !
*/

Compilation message (stderr)

Main.cpp:26:1: warning: multi-line comment [-Wcomment]
   26 | ////////////******SOLUTION******\\\\\\\\\\\
      | ^
Main.cpp: In function 'int main()':
Main.cpp:46:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |         for(int u = 0; u < adj[i].size(); u ++)
      |                        ~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42