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Submission #537468

# Submission time Handle Problem Language Result Execution time Memory
537468 2022-03-15T06:33:14 Z tqbfjotld Planine (COCI21_planine) C++14
110 / 110
 322 ms 82616 KB 
#include <bits/stdc++.h>
using namespace std;
#define int long long

vector<pair<int,int> > hull[2];

void add(int x, int y, int no){
    while (hull[no].size()>1){
        auto t1 = hull[no].back();
        auto t2 = *----hull[no].end();
        bool b = (y-t1.second)*(x-t2.first)>=(x-t1.first)*(y-t2.second);
        if (no) b = !b;
        if (b){
            hull[no].pop_back();
        }
        else break;
    }
    hull[no].push_back({x,y});
}

pair<int,int> qu(int x, int y, int no){
    if (hull[no].size()==1){
        return hull[no][0];
    }
    int l = -1;
    int r = hull[no].size()-1;
    while (l+1<r){
        int mid = (l+r)/2;
        auto t1 = hull[no][mid+1];
        auto t2 = hull[no][mid];
        bool b = (y-t1.second)*(x-t2.first)>=(x-t1.first)*(y-t2.second);
        if (no) b = !b;
        if (b) r = mid;
        else l = mid;
    }
    return hull[no][r];
}

struct frac{
    int a, b;
    frac(){}
    frac(int _a, int _b){
        a = _a; b = _b;
    }
    bool operator<(frac other){
        return a*other.b<other.a*b;
    }
    bool operator<=(frac other){
        return a*other.b<=other.a*b;
    }
    bool operator==(frac other){
        return a*other.b==other.a*b;
    }
};

bool cmp(pair<frac,frac> a, pair<frac,frac> b){
    if (a.first==b.first) return a.second<b.second;
    else return a.first<b.first;
}

int X[1000005];
int Y[1000005];
frac L[1000005];
frac R[1000005];

 main(){
    int n,h;
    scanf("%lld%lld",&n,&h);
    if (n==3) {
        printf("0");
        return 0;
    }
    for (int x = 0; x<n; x++){
        scanf("%lld%lld",&X[x],&Y[x]);
    }
    for (int x = 0; x<n; x++){
        if (x==0) continue;
        if (x==n-1) continue;
        if (x&1){
            add(X[x],Y[x],0);
        }
        else{
            auto res = qu(X[x],Y[x],0);
            //printf("res: %lld %lld\n",res.first,res.second);
            //res = {X[x-1],Y[x-1]};
            L[x] = frac(X[x]*(res.second-Y[x])-(h-Y[x])*(X[x]-res.first),res.second-Y[x]);
        }
    }
    for (int x = n-2; x>0; x--){
        if (x&1){
            add(X[x],Y[x],1);
        }
        else{
            auto res = qu(X[x],Y[x],1);
            //res = {X[x+1],Y[x+1]};
            R[x] = frac(X[x]*(res.second-Y[x])+(h-Y[x])*(res.first-X[x]),res.second-Y[x]);
        }
    }
    vector<pair<frac,frac> > intervals;
    for (int x = 2; x<n-1; x+=2){
        intervals.push_back({R[x],L[x]});
    }
    sort(intervals.begin(),intervals.end(),cmp);
    frac cur = intervals[0].first;
    int ans = 1;
    for (auto x : intervals){
        //printf("interval %lld/%lld to %lld/%lld\n",x.first.a,x.first.b,x.second.a,x.second.b);
        if (x.second<=cur) continue;
        ans++;
        cur = x.first;
    }
    printf("%lld",ans);
}

/*

9 7
-999 0
-998 4
-1 2
0 4
1 0
3 4
4 2
998 4
999 0

*/

Compilation message

Main.cpp:66:2: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   66 |  main(){
      |  ^~~~
Main.cpp: In function 'int main()':
Main.cpp:68:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |     scanf("%lld%lld",&n,&h);
      |     ~~~~~^~~~~~~~~~~~~~~~~~
Main.cpp:74:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         scanf("%lld%lld",&X[x],&Y[x]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1236 KB Output is correct
2 Correct 3 ms 1236 KB Output is correct
3 Correct 3 ms 1236 KB Output is correct
4 Correct 24 ms 7964 KB Output is correct
5 Correct 26 ms 7984 KB Output is correct
6 Correct 28 ms 8036 KB Output is correct
7 Correct 257 ms 71572 KB Output is correct
8 Correct 280 ms 71656 KB Output is correct
9 Correct 294 ms 71616 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 468 KB Output is correct
2 Correct 1 ms 468 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 468 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 1 ms 488 KB Output is correct
7 Correct 1 ms 340 KB Output is correct

Subtask #3
60.0 / 60.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1236 KB Output is correct
2 Correct 3 ms 1236 KB Output is correct
3 Correct 3 ms 1236 KB Output is correct
4 Correct 24 ms 7964 KB Output is correct
5 Correct 26 ms 7984 KB Output is correct
6 Correct 28 ms 8036 KB Output is correct
7 Correct 257 ms 71572 KB Output is correct
8 Correct 280 ms 71656 KB Output is correct
9 Correct 294 ms 71616 KB Output is correct
10 Correct 1 ms 468 KB Output is correct
11 Correct 1 ms 468 KB Output is correct
12 Correct 1 ms 340 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 0 ms 340 KB Output is correct
15 Correct 1 ms 488 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 280 ms 82616 KB Output is correct
18 Correct 264 ms 74708 KB Output is correct
19 Correct 28 ms 8364 KB Output is correct
20 Correct 266 ms 73892 KB Output is correct
21 Correct 28 ms 8148 KB Output is correct
22 Correct 289 ms 77588 KB Output is correct
23 Correct 1 ms 340 KB Output is correct
24 Correct 277 ms 76748 KB Output is correct
25 Correct 29 ms 8312 KB Output is correct
26 Correct 322 ms 77832 KB Output is correct
27 Correct 13 ms 4428 KB Output is correct