Submission #1279602

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279602		muhammad-mutahir	Airplane (NOI23_airplane)	C++20	0 / 100	1 ms	576 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#define print(l) for(auto i:l) cout<<i<<" ";cout<<endl;
#define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i];
#define int long long
#define pb push_back
#define all(l) l.begin(),l.end()
#define pii pair<int,int>
#define fi first
#define se second

const int M = 1e9+7;
const int inf = (int)1e18;
void io(){
    #ifndef ONLINE_JUDGE
    freopen("input.in","r",stdin);
    #endif
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    cout << fixed<<setprecision(9);
}

vector<vector<vector<int>>> adj;
vector<int> co;
int ans = inf;
int n , m;

priority_queue<vector<int>> pq;

void process_pq(){
    while(!pq.empty()){
        auto top = pq.top(); pq.pop();
        int ccost = -top[0];
        int u = top[1];
        int al = top[2];
        int canin = top[3];
        int inde = top[4];

        if(co[u] < ccost) continue;

        for(auto &x : adj[u]){
            int v = x[0];
            int ral = x[1];
            int acos = 0;
            int ncanin = canin;
            int ninde = inde;

            if(ral > al){
                int delta = ral - al - 1;
                int use = min(delta, ncanin);
                delta -= use; ncanin -= use;
                use = min(delta, ninde);
                delta -= use; ninde -= use;
                acos += delta;
                if(co[v] >= co[u] + acos + 1){
                    co[v] = co[u] + acos + 1;
                    if(v == n){
                        // arriving at region n; need to ensure landing height 0 accounted separately
                        ans = min(ans, co[v] + max(0ll, al - ninde));
                    }
                    pq.push({-co[v], v, ral, ncanin + ninde, 0});
                }
            }
            else if(ral == al){
                ncanin++;
                if(co[v] >= co[u] + acos + 1){
                    co[v] = co[u] + acos + 1;
                    if(v == n){
                        ans = min(ans, co[v]);
                    }
                    pq.push({-co[v], v, ral, ncanin + ninde, 0});
                }
            }
            else { // ral < al (descent)
                ninde++;
                // amount we can use from ninde to lower altitude difference
                int used = min(ninde, al - ral);
                ninde -= used;
                // x2 is the number used to close the gap; leftover (ninde) remains for other uses
                int x2 = used;
                if(co[v] >= co[u] + acos + 1){
                    co[v] = co[u] + acos + 1;
                    if(v == n){
                        ans = min(ans, co[v] + max(0ll, al - ninde));
                    }
                    // IMPORTANT: new altitude must be ral (region v's required minimum)
                    pq.push({-co[v], v, ral, ncanin + x2, ninde});
                }
            }
        }
    }
}

void solve(int testcase_number){
    cin>>n>>m;
    adj.clear();
    adj.resize(n+1);
    co.clear();
    co.resize(n+1, inf);
    co[1] = 0;
    input(int, l, n); // l holds a[1..n]

    for(int i = 0;i<m;i++){
        int u,v; cin>>u>>v;
        adj[u].pb({v, l[v-1]});
        adj[v].pb({u, l[u-1]});
    }

    while(!pq.empty()) pq.pop();
    pq.push({0,1,0,0,0});
    process_pq();

    if(ans == inf) cout << "-1\n";
    else cout << ans << "\n";
}

signed main(){
    // io();
    int t = 1;
    for(int i = 1;i<=t;i++){
        solve(i);
    }
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void io()':
Main.cpp:17:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     freopen("input.in","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 22
• Subtask 2: 0 / 10
• Subtask 3: 0 / 31
• Subtask 4: 0 / 37