oj.uz

Submission #227666

# Submission time Handle Problem Language Result Execution time Memory
227666 2020-04-28T11:09:27 Z nafis_shifat Building Bridges (CEOI17_building) C++14
100 / 100
 198 ms 5224 KB 
#include<bits/stdc++.h>
#define pii pair<int,int>
#define ll long long
using namespace std;
const int mxn=1e5+7;
vector<ll> m;
vector<ll> b;

ll h[mxn];
ll w[mxn];
ll p[mxn];

ll dp[mxn];

bool bad(int f1,int f2,int f3)
{
	return (b[f3]-b[f1])*(m[f1]-m[f2])<=(b[f2]-b[f1])*(m[f1]-m[f3]);
}

void add(ll m_,ll b_)
{       
	m.push_back(m_);
	b.push_back(b_);
	int sz=m.size();
	while(sz>=3 && bad(sz-3,sz-2,sz-1))
	{
		m.erase(m.end()-2);
		b.erase(b.end()-2);
		sz--;
	}
}

ll func(int p,ll x)
{
	return m[p]*x+b[p];
}
ll query(ll x)
{
    ll ans=1e18;
    int lo=0;
    int hi=m.size()-1;
    while(lo<=hi)
    {
     	int mid1=lo+(hi-lo)/3;
        int mid2=hi-(hi-lo)/3;
        if(func(mid1,x)<func(mid2,x))
        {
            ans=min(ans,func(mid1,x));
            hi=mid2-1;
        }
        else
        {
            ans=min(ans,func(mid2,x));
            lo=mid1+1;
        }
    }
    return ans;
}
void solve(int l,int r)
{
	if(l==r)return;
	int mid=l+r>>1;
	solve(l,mid);
	vector<int> v;
	for(int i=l;i<=mid;i++)v.push_back(i);
    m.clear();
    b.clear();
	sort(v.begin(),v.end(),[](int a,int b)
	{
	    if(h[a]==h[b])
	    {
	        return dp[a]+h[a]*h[a]-p[a]>dp[b]+h[b]*h[b]-p[b];
	    }
		return h[a]<h[b];
	});

    for(int i=0;i<v.size();i++)
    {
        
    	int k=v[i];
    	add(-2*h[k],dp[k]+h[k]*h[k]-p[k]);
    }

    for(int i=mid+1;i<=r;i++)
    {
    	dp[i]=min(dp[i],query(h[i])+h[i]*h[i]+p[i-1]);
    }

    
    solve(mid+1,r);
    

}


int main()
{
    for(int i=1;i<mxn;i++)dp[i]=1e18;
    dp[1]=0;
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)scanf("%lld",&h[i]);
	p[0]=0;
	for(int i=1;i<=n;i++)
	{
		scanf("%lld",&w[i]);
		p[i]=p[i-1]+w[i];
	}

	solve(1,n);

	cout<<dp[n]<<endl;
	return 0;
}

Compilation message

building.cpp: In function 'void solve(int, int)':
building.cpp:62:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~
building.cpp:77:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<v.size();i++)
                 ~^~~~~~~~~
building.cpp: In function 'int main()':
building.cpp:102:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=n;i++)scanf("%lld",&h[i]);
                       ~~~~~^~~~~~~~~~~~~~
building.cpp:106:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&w[i]);
   ~~~~~^~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 1152 KB Output is correct
2 Correct 5 ms 1152 KB Output is correct
3 Correct 5 ms 1152 KB Output is correct
4 Correct 6 ms 1152 KB Output is correct
5 Correct 6 ms 1152 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 198 ms 4332 KB Output is correct
2 Correct 188 ms 4388 KB Output is correct
3 Correct 193 ms 4464 KB Output is correct
4 Correct 179 ms 4452 KB Output is correct
5 Correct 119 ms 4856 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 1152 KB Output is correct
2 Correct 5 ms 1152 KB Output is correct
3 Correct 5 ms 1152 KB Output is correct
4 Correct 6 ms 1152 KB Output is correct
5 Correct 6 ms 1152 KB Output is correct
6 Correct 198 ms 4332 KB Output is correct
7 Correct 188 ms 4388 KB Output is correct
8 Correct 193 ms 4464 KB Output is correct
9 Correct 179 ms 4452 KB Output is correct
10 Correct 119 ms 4856 KB Output is correct
11 Correct 184 ms 4372 KB Output is correct
12 Correct 189 ms 4432 KB Output is correct
13 Correct 148 ms 4372 KB Output is correct
14 Correct 189 ms 4396 KB Output is correct
15 Correct 115 ms 5224 KB Output is correct
16 Correct 118 ms 4856 KB Output is correct
17 Correct 81 ms 4448 KB Output is correct
18 Correct 89 ms 4420 KB Output is correct