Submission #743942

#	Time	Username	Problem	Language	Result	Execution time	Memory
743942		josanneo22	Crocodile's Underground City (IOI11_crocodile)	C++17	100 / 100	443 ms	45296 KiB

crocodile

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

#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define fi first
#define se second  

const int mxn = 1e5;
const int inf = 1e9 + 3;
vector<pii>adj[mxn + 1];
pii d[mxn + 1];
struct ch {
    int u, d;
};
struct cmp {
    bool operator()(ch a, ch b) {
        return(a.d > b.d);
    }
};
/*
    from subtask 1: only the second answer matters
    do djikstra from each of the exit nodes 
    by sorting ascending values of the second answer
*/
int travel_plan(int n, int m, int r[][2], int l[], int k, int p[]) {
    for (int i = 0; i < n; i++) {
        d[i].fi = d[i].se = inf;
    }
    for (int i = 0; i < m; i++) {
        int u = r[i][0], v = r[i][1], w = l[i];
        adj[u].pb({ v, w }); adj[v].pb({ u, w });
    }
    priority_queue<ch, vector<ch>, cmp>pq;
    //first is index, second is weight accumlated
    for (int i = 0; i < k; i++) {
        d[p[i]].fi = d[p[i]].se = 0;
        pq.push({ p[i], 0 });
    }
    while (!pq.empty()) {
        ch nw = pq.top(); pq.pop();
        int u = nw.u, dd = nw.d;
        if (u == 0) {
            return (dd);
        }
        if (d[u].se < dd)continue;
        for (auto i : adj[u]) {
            int v = i.fi, w = i.se;
            if (dd + w < d[v].se) {
                int cr = d[v].se;
                d[v].se = dd + w;
                if (d[v].fi > d[v].se) swap(d[v].fi, d[v].se);//remember to swap
                if (d[v].se < cr) {//if there is a change
                    pq.push({ v, d[v].se });
                }
            }
        }
    }
}

Compilation message (stderr)

crocodile.cpp: In function 'int travel_plan(int, int, int (*)[2], int*, int, int*)':
crocodile.cpp:38:40: warning: control reaches end of non-void function [-Wreturn-type]
   38 |     priority_queue<ch, vector<ch>, cmp>pq;
      |                                        ^~

• Subtask 1: 46 / 46
• Subtask 2: 43 / 43
• Subtask 3: 11 / 11