more stuff

5 files changed, 121 insertions, 6 deletions

diff --git a/content/geometry/segmentIntersection.cpp b/content/geometry/segmentIntersection.cpp
index acce7cc..afc01b2 100644
--- a/content/geometry/segmentIntersection.cpp
+++ b/content/geometry/segmentIntersection.cpp
@@ -29,7 +29,7 @@ bool lessPT(const pt& a, const pt& b) {
 }
 
 bool intersect(const seg& a, const seg& b) {
-	return lineSegmentIntersection(a.a, a.b, b.a, b.b);
+	return segmentIntersection(a.a, a.b, b.a, b.b); //@\sourceref{geometry/linesAndSegments.cpp}@
 }
 
 pair<int, int> intersect(vector<seg>& segs) {
diff --git a/content/graph/dinic.cpp b/content/graph/dinic.cpp
new file mode 100644
index 0000000..2e58a2d
--- /dev/null
+++ b/content/graph/dinic.cpp
@@ -0,0 +1,55 @@
+struct Edge {
+	int to, rev;
+	ll f, c;
+};
+
+vector<vector<Edge>> adj;
+int s, t;
+vector<int> pt, dist;
+
+void addEdge(int u, int v, ll c) {
+	adj[u].push_back({v, (int)sz(adj[v]), 0, c});
+	adj[v].push_back({u, (int)sz(adj[u]) - 1, 0, 0});
+}
+
+bool bfs() {
+	dist.assign(sz(adj), -1);
+	dist[s] = 0;
+	queue<int> q({s});
+	while (!q.empty() && dist[t] < 0) {
+		int v = q.front(); q.pop();
+		for (Edge& e : adj[v]) {
+			if (dist[e.to] < 0 && e.c - e.f > 0) {
+				dist[e.to] = dist[v] + 1;
+				q.push(e.to);
+	}}}
+	return dist[t] >= 0;
+}
+
+ll dfs(int v, ll flow = INF) {
+	if (v == t || flow == 0) return flow;
+	for (; pt[v] < sz(adj[v]); pt[v]++) {
+		Edge& e = adj[v][pt[v]];
+		if (dist[e.to] != dist[v] + 1) continue;
+		ll cur = dfs(e.to, min(e.c - e.f, flow));
+		if (cur > 0) {
+			e.f += cur;
+			adj[e.to][e.rev].f -= cur;
+			return cur;
+	}}
+	return 0;
+}
+
+ll maxFlow(int source, int target) {
+	s = source, t = target;
+	ll flow = 0;
+	while (bfs()) {
+		pt.assign(sz(adj), 0);
+		ll cur;
+		do {
+			cur = dfs(s);
+			flow += cur;
+		} while (cur > 0);
+	}
+	return flow;
+}
diff --git a/content/string/duval.cpp b/content/string/duval.cpp
index bf36cce..253bae1 100644
--- a/content/string/duval.cpp
+++ b/content/string/duval.cpp
@@ -6,9 +6,8 @@ vector<pair<int, int>> duval(const string& s) {
 			if (s[k] < s[j]) k = i;
 			else k++;
 		}
-		while (i <= k) {
+		for (; i <= k; i += j - k) {
 			res.push_back({i, i + j - k});
-			i += j - k;
 	}}
 	return res;
 }
@@ -16,6 +15,5 @@ vector<pair<int, int>> duval(const string& s) {
 int minrotation(const string& s) {
 	auto parts = duval(s+s);
 	for (auto [l, r] : parts) {
-		if (l < sz(s) && r >= sz(s)) {
-			return l;
-}}}
+		if (r >= sz(s)) return l;
+}}
diff --git a/tcr.pdf b/tcr.pdf
index 199c3de..2f24510 100644
--- a/tcr.pdf
+++ b/tcr.pdf
diff --git a/test/graph/dinic.cpp b/test/graph/dinic.cpp
new file mode 100644
index 0000000..5af7c6f
--- /dev/null
+++ b/test/graph/dinic.cpp
@@ -0,0 +1,62 @@
+#include "../util.h"
+constexpr ll INF = LL::INF;
+namespace dinic {
+#include <graph/dinic.cpp>
+}
+
+namespace pushRelabel {
+#include <graph/pushRelabel.cpp>
+}
+
+void stress_test() {
+	ll queries = 0;
+	for (int tries = 0; tries < 20'000; tries++) {
+		int n = Random::integer<int>(2, 30);
+		int m = Random::integer<int>(n-1, max<int>(n, min<int>(500, n*(n-1) / 2 + 1)));
+
+		dinic::adj.assign(n, {});
+		pushRelabel::adj.assign(n, {});
+
+		Graph<NoData, true> g(n);
+		g.erdosRenyi(m);
+		g.forEdges([](int a, int b){
+			ll w = Random::integer<ll>(1, 1'000'000'000'000ll);
+			dinic::addEdge(a, b, w);
+			pushRelabel::addEdge(a, b, w);
+		});
+
+		ll got = dinic::maxFlow(0, n - 1);
+		ll expected = pushRelabel::maxFlow(0, n - 1);
+		
+		if (got != expected) cerr << "got: " << got << ", expected: " << expected << FAIL;
+		queries += n;
+	}
+	cerr << "tested random queries: " << queries << endl;
+}
+
+constexpr int N = 50000;
+constexpr int M = 200000;
+void performance_test() {
+	using namespace dinic;
+	timer t;
+	Graph<NoData> g(N);
+	g.erdosRenyi(M);
+	adj.assign(N, {});
+	g.forEdges([](int a, int b){
+		ll w1 = Random::integer<ll>(1, 1'000'000'000'000ll);
+		ll w2 = Random::integer<ll>(1, 1'000'000'000'000ll);
+		addEdge(a, b, w1);
+		addEdge(b, a, w2);
+	});
+
+	t.start();
+	hash_t hash = maxFlow(0, N - 1);
+	t.stop();
+	if (t.time > 2000) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	stress_test();
+	performance_test();
+}