Submission #260856

#	Time	Username	Problem	Language	Result	Execution time	Memory
260856		jeqcho	Palembang Bridges (APIO15_bridge)	C++17	31 / 100	2086 ms	2456 KiB

bridge

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

typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define f first
#define s second

vpi cross;

ll build(int bri)
{
    ll val=0;
    trav(e, cross)
    {
        val += (ll)(e.s-e.f+1);
        if(bri>e.s)
        {
            val += (ll)(bri - e.s) * (ll)2;
        }
        else if(bri<e.f)
        {
            val += (ll)(e.f - bri) * (ll)2;
        }
    }
    return val;
}

ll build2(int lb, int rb)
{
    ll val=0;
    ll lcand,rcand;
    trav(e, cross)
    {
        val += (ll)(e.s-e.f+1);
        lcand=rcand=0;
        if(lb>e.s)
        {
            lcand += (ll)(lb - e.s) * (ll)2;
        }
        else if(lb<e.f)
        {
            lcand += (ll)(e.f - lb) * (ll)2;
        }
        if(rb>e.s)
        {
            rcand += (ll)(rb - e.s) * (ll)2;
        }
        else if(rb<e.f)
        {
            rcand += (ll)(e.f - rb) * (ll)2;
        }
        val += min(lcand,rcand);
    }
    return val;
}

bool ok(int now)
{
    ll g = build(now+1) - build(now);
    if(g<0)return 1;
    else return 0;
}

bool check(int lb, int rb, int lef, int rig)
{
    if(lef)
    if(build2(lb+lef,rb+rig)-build2(lb,rb)<0)return 1;
    else return 0;
}

ll test(int lr, int rr)
{
    int rb = cross[rr].s;
    int lef = cross[lr].f;
    int rig = cross[lr].s;
    int mid;
    while(lef<=rig)
    {
        mid=(lef+rig)/2;
        if(check(mid, rb, 1,0))lef=mid+1;
        else rig=mid-1;
    }
    int lb = lef;
    lef = cross[rr].f;
    rig = cross[rr].s;
    while(lef<=rig)
    {
        mid=(lef+rig)/2;
        if(check(lb, mid, 0,1))lef=mid+1;
        else rig=mid-1;
    }
    rb = lef;
    ll ans=2e18;
    FOR(i,max(0,lb-5),min((int)1e9+1,lb+5))
    {
        FOR(j,max(0,rb-5),min((int)1e9+1,rb+5))
        {
            ans = min(ans, build2(lb,rb));
        }
    }
    return ans;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    int K,N;
    cin>>K>>N;
    char P[N],Q[N];
    int S[N],T[N];
    ll base=0;
    F0R(i,N)
    {
        cin>>P[i]>>S[i]>>Q[i]>>T[i];
        if(P[i]==Q[i])
        {
            base += (ll)( max(S[i],T[i]) - min(S[i],T[i]) );
        }
        else
        {
            cross.pb({min(S[i],T[i]), max(S[i],T[i])});
        }
    }
    ll ans;
    if(K==2)
    {
        ans = 2e14+5;
        sort(all(cross));
        F0R(i,sz(cross))
        {
            FOR(j,i+1,sz(cross))
            {
                ans=min(ans,test(i,j));
            }
        }
    }
    else
    {
        int lef=0,rig=1e9;
        int mid;
        while(lef<=rig)
        {
            mid=(lef+rig)/2;
            if(ok(mid))lef=mid+1;
            else rig=mid-1;
        }
        ans = 2e14+5;
        FOR(i,max(0,lef-10),min((int)1e9+1,lef+10))
        {
            ans=min(ans,build(i));
        }
    }
    if(ans==2e14+5)ans=0;
    ans+=base;
    cout<<ans<<'\n';
    return 0;
}

Compilation message (stderr)

bridge.cpp: In function 'bool check(int, int, int, int)':
bridge.cpp:80:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
     if(lef)
       ^
bridge.cpp:83:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

• Subtask 1: 8 / 8
• Subtask 2: 14 / 14
• Subtask 3: 9 / 9
• Subtask 4: 0 / 32
• Subtask 5: 0 / 37