Submission #64795

#	Time	Username	Problem	Language	Result	Execution time	Memory
64795		bazsi700	The Forest of Fangorn (CEOI14_fangorn)	C++14	100 / 100	317 ms	1308 KiB

fangorn

#include <bits/stdc++.h>

using namespace std;
#define ll long long
#define C complex<ll>
#define X real()
#define Y imag()

ll w,h,n,c;
C g;
C camp[10005];
C tree[10005];
bool can[15];

int sign(ll x) {
    if(x > 0) {
        return 1;
    } else if(x == 0) {
        return 0;
    } else {
        return -1;
    }
}

ll cross(C a, C b) { //-1 bal, 0 egyenes, 1 jobb A hoz képest a B
    return sign(((a*conj(b)).Y));
}

bool isbadv[10005];
int leftest[10005];
int rightest[10005];
int leftof[10005];
int rightof[10005];

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll gx,gy;
    cin >> w >> h >> gx >> gy >> c;
    g = {gx,gy};
    for(int i = 0; i < c; i++) {
        ll x,y;
        cin >> x >> y;
        camp[i] = {x,y};
    }
    cin >> n;
    for(int i = 0; i < n; i++) {
        ll x,y;
        cin >> x >> y;
        tree[i] = {x,y};
    }
    for(int i = 0; i < n; i++) {
        bool bad = false;
        int fix = (i == 0 ? 1 : 0);
        for(int j = 0; j < n; j++) {
            if(j == i || j == fix) {
                continue;
            }
            if(cross(tree[fix]-tree[i],tree[j]-tree[i]) > 0) {
                fix = j;
            }
        }
        for(int j = 0; j < n; j++) {
            if(j == i || j == fix) {
                continue;
            }
            if(cross(tree[fix]-tree[i],tree[j]-tree[i]) > 0) {
                bad = true;
            }
        }
        if(bad) {
            int left1 = -1;
            for(int x = 0; x < n; x++) {
                if(x == i) {
                    continue;
                }
                if(cross(tree[i]-g,tree[x]-tree[i]) < 0) {
                    if(left1 == -1 || cross(tree[x]-tree[i],tree[left1]-tree[i]) < 0) {
                        left1 = x;
                    }
                }
            }
            leftof[i] = left1;
            int right1 = -1;
            for(int x = 0; x < n; x++) {
                if(x == i) {
                    continue;
                }
                if(cross(tree[i]-g,tree[x]-tree[i]) > 0) {
                    if(right1 == -1 || cross(tree[x]-tree[i],tree[right1]-tree[i]) > 0) {
                        right1 = x;
                    }
                }
            }
            rightof[i] = right1;
            isbadv[i] = true;
        } else {
            leftest[i] = fix;
        }
    }
    for(int i = 0; i < n; i++) {
        if(isbadv[i]) {
            continue;
        }
        int fix = (i == 0 ? 1 : 0);
        for(int j = 0; j < n; j++) {
            if(j == i || j == fix) {
                continue;
            }
            if(cross(tree[fix]-tree[i],tree[j]-tree[i]) < 0) {
                fix = j;
            }
        }
        rightest[i] = fix;
        //cout << i << " " << leftest[i] << " " << rightest[i] << "a\n";
    }
    vector<int> pr;
    for(int i = 0; i < c; i++) {
        bool good = true;
       /* for(int x = 0; x < n; x++) {
            for(int y = x+1; y < n; y++) {
                if(isbad[x][y]) {
                    if(cross(tree[y]-tree[x],g-tree[x]) == -cross(tree[y]-tree[x],camp[i]-tree[x])) {
                        good = false;
                    }
                }
            }
        }
       // cout << good << "\n";
        if(!good) {
            continue;
        }*/
        for(int a2 = 0; a2 < n && good; a2++) {
            if(!isbadv[a2]) {
                int b1 = a2;
                int a1 = leftest[a2];
                int b2 = rightest[a2];
                if(b2 == a1 || b2 == a2) {
                    continue;
                }
                if(cross(tree[a2]-tree[a1],camp[i]-tree[a1]) != -cross(tree[a2]-tree[a1],g-tree[a1]) && cross(tree[b2]-tree[b1],camp[i]-tree[b1]) != -cross(tree[b2]-tree[b1],g-tree[b1])) {
                    continue;
                }
                if(cross(tree[a2]-tree[a1],tree[b2]-tree[a1]) == -cross(tree[a2]-tree[a1],camp[i]-tree[a1]) && cross(tree[b2]-tree[b1],tree[a1]-tree[b1]) == -cross(tree[b2]-tree[b1],camp[i]-tree[b1])) {
                    good = false;
                 //   cout << a1 << " " << b1 << " " << b2 << endl;
                }
                if(cross(tree[a2]-tree[a1],tree[b2]-tree[a1]) == -cross(tree[a2]-tree[a1],g-tree[a1]) && cross(tree[b2]-tree[b1],tree[a1]-tree[b1]) == -cross(tree[b2]-tree[b1],g-tree[b1])) {
                    good = false;
               //     cout << a1 << " " << b1 << " " << b2 << endl;
                }
            } else {
                int left1 = leftof[a2];
                int right1 = rightof[a2];
                if(cross(tree[a2]-camp[i],tree[left1]-tree[a2]) > 0 || cross(tree[a2]-camp[i],tree[right1]-tree[a2]) < 0) {
                    good = false;
                }


               // if(i == 2) {
                //    cout << left1 << " " << left2 << endl;
                //}
            }
        }
        if(good) {
            pr.push_back(i+1);
        }
    }
    cout << pr.size() << "\n";
    for(int el : pr) {
        cout << el << " ";
    }
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 20 / 20