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Submission #56193

# Submission time Handle Problem Language Result Execution time Memory
56193 2018-07-10T08:22:44 Z 노영훈(#1580) Mobile (BOI12_mobile) C++11
62 / 100
 397 ms 32892 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double lf;
typedef pair<ll, ll> pll;
const int MX=1000010, inf=2e9;
const ll linf=5e18;

int n;
ll l;
pll P[MX];

ll sq(ll x){ return x*x; }

lf itst(pll a, pll b){
    lf dm=a.first-b.first, db=a.second-b.second;
    return -db/dm;
}
lf eval(pll a, lf x){
    return a.first*x + a.second + x*x;
}

int main(){
    ios::sync_with_stdio(0); cin.tie(0);
    cin>>n>>l;
    for(int i=1; i<=n; i++){
        ll x, y; cin>>x>>y;
        P[i]={-2*x,x*x+y*y};
    }
    sort(P+1, P+n+1, [](pll &a, pll &b){
        if(a.first==b.first) return a.second>b.second;
        return a.first>b.first;
    });
    // for(int i=1; i<=n; i++) cout<<P[i].first<<' '<<P[i].second<<'\n';
    vector<pll> stk; // m, b
    stk.push_back({0, linf});
    for(int i=1; i<=n; i++){
        pll now=P[i];
        while(!stk.empty()){
            pll prv=stk.back(); stk.pop_back();
            if(now.first==prv.first) continue;
            if(!stk.empty() && itst(stk.back(), prv)>=itst(prv, now)) continue;
            else { stk.push_back(prv); break; }
        }
        stk.push_back(P[i]);
    }


    lf ans=0;
    lf prv=-linf;
    for(int i=1; i<(int)stk.size(); i++){
        lf x=itst(stk[i-1], stk[i]);
        // cout<<stk[i].first<<' '<<stk[i].second<<": "<<x<<'\n';
        if(x<0){ prv=x; continue; }
        if(prv<0){ ans=max(ans, eval(stk[i-1], 0)); }
        if(x>l){ ans=max(ans, eval(stk[i-1], l)); break; }
        ans=max(ans, eval(stk[i], x));
        prv=x;
    }
/*

    lf prv=-linf, ans=0;
    for(int i=1; i<(int)stk.size(); i++){
        lf now=itst(stk[i], stk[i-1]);
        // cout<<now<<'\n';
        // cout<<now<<' '<<eval(stk[i], now)<<'\n';
        if(now<0) continue;
        if(prv<0 && 0<=now){
            prv=now;
            ans=max(ans, eval(stk[i-1], 0));
        }
        if(l<now){
            ans=max(ans, eval(stk[i-1], l));
            break;
        }
        // cout<<now<<' '<<eval(stk[i], now)<<'\n';
        ans=max(ans, eval(stk[i], now));
        // cout<<'\n';
    }
    // cout<<'\n';
    // for(int i=0; i<(int)stk.size(); i++) cout<<stk[i].first<<' '<<stk[i].second<<'\n';

    // if(stk.size()==1U) ans=max({ans, eval(stk[0], 0), eval(stk[0], l)});
    // if(stk.size()>1U && itst(stk[0], stk[1])<=0) ans=max(ans, eval(stk[0], 0));
    // if(stk.size()>1U && itst(stk.back(), stk[stk.size()-2])>=l) ans=max(ans, eval(stk.back(), l));
    */
    cout.precision(5);
    cout<<fixed<<sqrtl(ans);
    return 0;
}

Subtask #1
0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 376 KB Output is correct
2 Correct 2 ms 376 KB Output is correct
3 Correct 3 ms 416 KB Output is correct
4 Incorrect 2 ms 540 KB Output isn't correct

Subtask #2
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 540 KB Output is correct
2 Correct 2 ms 540 KB Output is correct
3 Correct 2 ms 600 KB Output is correct
4 Correct 3 ms 600 KB Output is correct

Subtask #3
0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 600 KB Output is correct
2 Incorrect 3 ms 692 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #4
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 692 KB Output is correct
2 Correct 4 ms 692 KB Output is correct
3 Correct 4 ms 692 KB Output is correct
4 Correct 4 ms 692 KB Output is correct

Subtask #5
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 704 KB Output is correct
2 Correct 3 ms 748 KB Output is correct
3 Correct 3 ms 748 KB Output is correct
4 Correct 3 ms 748 KB Output is correct

Subtask #6
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 748 KB Output is correct
2 Correct 3 ms 748 KB Output is correct
3 Correct 4 ms 748 KB Output is correct
4 Correct 5 ms 748 KB Output is correct
5 Correct 4 ms 748 KB Output is correct

Subtask #7
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 1956 KB Output is correct
2 Correct 27 ms 1956 KB Output is correct
3 Correct 19 ms 1956 KB Output is correct
4 Correct 33 ms 1956 KB Output is correct
5 Correct 29 ms 1956 KB Output is correct

Subtask #8
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 1956 KB Output is correct
2 Correct 24 ms 1956 KB Output is correct
3 Correct 23 ms 1956 KB Output is correct
4 Correct 29 ms 1956 KB Output is correct
5 Correct 29 ms 1956 KB Output is correct

Subtask #9
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 22 ms 4212 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #10
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 29 ms 4212 KB Output is correct
2 Correct 28 ms 4212 KB Output is correct
3 Correct 35 ms 4212 KB Output is correct
4 Correct 40 ms 4212 KB Output is correct
5 Correct 30 ms 4212 KB Output is correct

Subtask #11
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 38 ms 4212 KB Output is correct
2 Correct 34 ms 4212 KB Output is correct
3 Correct 42 ms 4212 KB Output is correct
4 Correct 40 ms 4212 KB Output is correct
5 Correct 34 ms 4212 KB Output is correct

Subtask #12
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 157 ms 16756 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #13
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 175 ms 16756 KB Output is correct
2 Correct 181 ms 16756 KB Output is correct
3 Correct 143 ms 16756 KB Output is correct
4 Correct 217 ms 16756 KB Output is correct
5 Correct 172 ms 16756 KB Output is correct

Subtask #14
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 178 ms 26720 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #15
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 187 ms 26720 KB Output is correct
2 Correct 236 ms 26720 KB Output is correct
3 Correct 161 ms 26720 KB Output is correct
4 Correct 207 ms 26720 KB Output is correct
5 Correct 173 ms 26720 KB Output is correct

Subtask #16
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 174 ms 28076 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #17
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 207 ms 28076 KB Output is correct
2 Correct 186 ms 28076 KB Output is correct
3 Correct 184 ms 28076 KB Output is correct
4 Correct 234 ms 28076 KB Output is correct
5 Correct 233 ms 28076 KB Output is correct

Subtask #18
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 195 ms 29656 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #19
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 240 ms 29656 KB Output is correct
2 Correct 245 ms 29656 KB Output is correct
3 Correct 316 ms 29656 KB Output is correct
4 Correct 358 ms 29656 KB Output is correct
5 Correct 239 ms 29656 KB Output is correct

Subtask #20
0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 275 ms 32892 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #21
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 397 ms 32892 KB Output is correct
2 Correct 348 ms 32892 KB Output is correct
3 Correct 326 ms 32892 KB Output is correct
4 Correct 367 ms 32892 KB Output is correct
5 Correct 376 ms 32892 KB Output is correct