3 files changed, 134 insertions, 0 deletions
diff --git a/17/day4/knights.cpp b/17/day4/knights.cpp
new file mode 100644
index 0000000..784abfc
--- /dev/null
+++ b/17/day4/knights.cpp
@@ -0,0 +1,91 @@
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+constexpr ll INF = 1e12;
+ 
+int dx[] = { 2, 1, -1, -2, -2, -1, 1, 2 };
+int dy[] = { 1, 2, 2, 1, -1, -2, -2, -1 };
+char A[101][101];
+ 
+template<int V, class T = ll> class max_flow {
+	struct edge {
+		int t, rev;
+		T cap, f;
+	};
+	vector<edge> adj[V];
+	int dist[V];
+	int ptr[V];
+	bool bfs(int s, int t) {
+		memset(dist, -1, sizeof dist);
+		dist[s] = 0;
+		queue<int> q({ s });
+		while (!q.empty() && dist[t] == -1) {
+			int n = q.front();
+			q.pop();
+			for (auto& e : adj[n]) {
+				if (dist[e.t] == -1 && e.cap != e.f) {
+					dist[e.t] = dist[n] + 1;
+					q.push(e.t);
+				}
+			}
+		}
+		return dist[t] != -1;
+	}
+	T augment(int n, T amt, int t) {
+		if (n == t) return amt;
+		for (; ptr[n] < adj[n].size(); ptr[n]++) {
+			edge& e = adj[n][ptr[n]];
+			if (dist[e.t] == dist[n] + 1 && e.cap != e.f) {
+				T flow = augment(e.t, min(amt, e.cap - e.f), t);
+				if (flow != 0) {
+					e.f += flow;
+					adj[e.t][e.rev].f -= flow;
+					return flow;
+				}
+			}
+		}
+		return 0;
+	}
+public:
+	void add(int u, int v, T cap = 1, T rcap=0) {
+		adj[u].push_back({ v, (int) adj[v].size(), cap, 0 });
+		adj[v].push_back({ u, (int) adj[u].size() - 1, rcap, 0 });
+	}
+	T calc(int s, int t) {
+		T flow = 0;
+		while (bfs(s, t)) {
+			memset(ptr, 0, sizeof ptr);
+			while (T df = augment(s, INF, t)) flow += df;
+		}
+		return flow;
+	}
+	void clear() {
+		for (int n = 0; n < V; n++) adj[n].clear();
+	}
+};
+ 
+int main() {
+	int R, C; 
+	cin >> R >> C;
+	int ans = R * C;
+	for (int i = 0; i < R; ++i) {
+		for (int j = 0; j < C; ++j) cin >> A[i][j];
+	}
+ 
+	max_flow<101*101> MF;
+	for (int i = 0; i < R; ++i) {
+		for (int j = 0; j < C; ++j) {
+			if (A[i][j] == '#') { --ans; continue; }
+			if (i + j & 1) {
+				MF.add(10000, i * C + j, (A[i][j] == 'C' ? INF : 1));
+				for (int d = 0; d < 8; ++d) {
+					int x = i + dx[d], y = j + dy[d];
+					if (x < 0 || x >= R || y < 0 || y >= C || A[x][y] == '#') continue;
+					MF.add(i * C + j, x * C + y, INF);
+				}
+			}
+			else MF.add(i * C + j, 10001, (A[i][j] == 'C' ? INF : 1));
+		}
+	}
+	cout << ans - MF.calc(10000, 10001) << '\n';
+}
+\ No newline at end of file
diff --git a/17/day4/stock_trading.cpp b/17/day4/stock_trading.cpp
new file mode 100644
index 0000000..c2aa679
--- /dev/null
+++ b/17/day4/stock_trading.cpp
@@ -0,0 +1,21 @@
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+int main() {
+	ios_base::sync_with_stdio(0), cin.tie(0);
+
+	int N, L;
+	cin >> N >> L;
+
+	multiset<ll> S;
+	ll ans = 0;
+	for (int i = 0, b, s; i < N; ++i) {
+		cin >> b >> s;
+		ans = max(ans - (i >= L ? *begin(S) : 0) + s, ans);
+		S.insert({ b, s });
+		if (i >= L) S.erase(begin(S)), S.erase(prev(end(S)));
+	}
+	for (auto it = S.begin(); L; ++it, --L) ans -= *it;
+	cout << ans << endl;
+}
+\ No newline at end of file
diff --git a/17/day4/tuning.cpp b/17/day4/tuning.cpp
new file mode 100644
index 0000000..d2bddd9
--- /dev/null
+++ b/17/day4/tuning.cpp
@@ -0,0 +1,22 @@
+#include <bits/stdc++.h>
+using namespace std;
+ 
+int main() {
+	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
+ 
+	int N;
+	cin >> N;
+	int ans = 1, cnt = 1;
+	for (int i = 2; i < N; ++i) {
+		if (cnt) {
+			cout << ans << ' ' << i << endl;
+			string s; cin >> s;
+			s[0] == 'S' ? ++cnt : --cnt;
+		}
+		else {
+			ans = i;
+			++cnt;
+		}
+	}
+	cout << (cnt ? ans : N) << endl;
+}
+\ No newline at end of file