Submission #266663

#	Time	Username	Problem	Language	Result	Execution time	Memory
266663		sealnot123	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	381 ms	42212 KiB

railroad

#include "railroad.h"
#include<bits/stdc++.h>
#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define all(a) (a).begin(),(a).end()
#define SZ(a) (int)(a).size()
#define FOR(i, a, b) for(int i=(a); i<=(b); ++i)
#define ROF(i, a, b) for(int i=(a); i>=(b); --i)
#define make_unique(a) sort(all((a))), (a).resize(unique(all((a)))-(a).begin())

using namespace std;

typedef pair<int,int> PII;
typedef long long LL;
typedef double DD;
typedef long double LD;
typedef pair<LL,LL> PLL;
typedef pair<DD,DD> PDD;
typedef vector<int> VI;
typedef vector<LL> VL;

const int N = 400004;
int n;
LL plan_roller_coaster(VI s, VI t) {
    int n = SZ(s);
    vector<int> cmp;
    FOR(i, 0, n-1) cmp.pb(s[i]), cmp.pb(t[i]);
    cmp.pb(0); cmp.pb(1e9+2);
    make_unique(cmp);
    FOR(i, 0, n-1){
        s[i] = lower_bound(all(cmp), s[i])-cmp.begin();
        t[i] = lower_bound(all(cmp), t[i])-cmp.begin();
    }
    LL ans = 0;
    int m = SZ(cmp);
    vector<int> dp(m);
    vector<VI> g(m);
    FOR(i, 0, n-1){ 
        g[s[i]].pb(t[i]);
        dp[s[i]]++; dp[t[i]]--;
        //printf("(%d, %d)\n",s[i],t[i]);
    }
    FOR(i, 0, m-2){
        if(i != 0) dp[i] += dp[i-1];
        //printf("%d ",dp[i]);
        if(dp[i] > 1) ans += (dp[i]-1)*1ll*(cmp[i+1]-cmp[i]), g[i+1].pb(i);
        if(dp[i] < 1) g[i].pb(i+1);
    }
    //puts("");
    //printf("%lld\n",ans);
    // mst lets gooo
    queue<int> bfs;
    vector<int> comp(m);
    int cnt = 0;
    FOR(i, 0, m-1){
        if(comp[i]) continue;
        ++cnt;
        comp[i] = cnt;
        bfs.push(i);
        while(!bfs.empty()){
            int u = bfs.front();
            bfs.pop();
            for(int e : g[u]){
                if(comp[e]) continue;
                comp[e] = cnt;
                bfs.push(e);
            }
        }
    }
    vector< pair<int,PII> > edges; // for mst
    vector<int> dsu(cnt+1);
    FOR(i, 1, cnt) dsu[i] = i;
    function<int(int)> find = [&](int i){
        //printf("==%d %d\n",dsu[i],i);
        if(dsu[i] == i) return i;
        return dsu[i] = find(dsu[i]);
    };
    FOR(i, 1, m-2){
        //printf("[%d]\n",comp[i]);
        if(comp[i-1] != comp[i]){
            edges.pb({cmp[i]-cmp[i-1], PII(comp[i-1], comp[i])});
        }
        if(comp[i] != comp[i+1]){
            edges.pb({cmp[i+1]-cmp[i], PII(comp[i+1], comp[i])});
        }
    }
    sort(all(edges));
    for(auto &f : edges){
        LL cost = f.x;
        int a, b;
        tie(a, b) = f.y;
        if(find(a) != find(b)){
            ans += cost;
            dsu[find(a)] = find(b);
        }
    }
    return ans;
}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 36 / 36