[20251030] BOJ / P5 / Pineapple Pizza / 권혁준

khj20006/202510/30 BOJ P5 Pineapple Pizza.md

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+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<pair<int, int>> p, u, l;
+int N, K;
+
+int ccw(pair<long long, long long> a, pair<long long, long long> b, pair<long long, long long> c) {
+    auto [ax, ay] = a;
+    auto [bx, by] = b;
+    auto [cx, cy] = c;
+    long long res = ax*by + bx*cy + cx*ay - (ax*cy + bx*ay + cx*by);
+    if(res > 0) return 1;
+    if(res < 0) return -1;
+    return 0;
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+
+    cin>>N>>K;
+    if(N%K) return cout<<"NO",0;
+    p.resize(N);
+    for(auto &[x,y]:p) cin>>x>>y;
+    int _x, _y;
+    cin>>_x>>_y;
+    for(auto &[x,y]:p) {
+        x-=_x, y-=_y;
+        if(y < 0 || (y == 0 && x < 0)) l.emplace_back(x,y);
+        else u.emplace_back(x,y);
+    }
+
+    sort(u.begin(), u.end(), [](auto a, auto b) -> bool {
+        return ccw({0,0}, a, b) < 0;
+    });
+    sort(l.begin(), l.end(), [](auto a, auto b) -> bool {
+        return ccw({0,0}, a, b) < 0;
+    });
+
+    deque<int> a;
+    for(int i=1;i<u.size();i++) {
+        int cnt = 1;
+        while(i<u.size() && !ccw({0,0}, u[i-1], u[i])) cnt++, i++;
+        a.push_back(cnt);
+    }
+    for(int i=1;i<l.size();i++) {
+        int cnt = 1;
+        while(i<l.size() && !ccw({0,0}, l[i-1], l[i])) cnt++, i++;
+        a.push_back(cnt);
+    }
+
+    for(int c=0;c<N;c++) {
+        a.push_back(a.front());
+        a.pop_front();
+        int cur = 0;
+        bool poss = 1;
+        for(int i:a) {
+            cur += i;
+            if(cur == N/K) cur = 0;
+            else if(cur > N/K) {
+                poss = 0;
+                break;
+            }
+        }
+        if(poss) return cout<<"YES", 0;
+    }
+    cout<<"NO";
+
+}
+```