teamnote history merge

2025fall/source/Graph/DominatorTree.cpp

@@ -0,0 +1,51 @@
+// https://ideone.com/aO6cH4
+namespace dtree{  // by cki86201
+vector<int> E[N], RE[N], rdom[N];
+int S[N], RS[N], cs;
+int par[N], val[N], sdom[N], rp[N], dom[N];
+void clear(int n) { cs = 0;
+    for(int i=0;i<=n;i++) {
+        par[i] = val[i] = sdom[i] = rp[i] = dom[i] = S[i] = RS[i] = 0;
+        E[i].clear(); RE[i].clear(); rdom[i].clear();
+    }
+}
+void add_edge(int x, int y) { E[x].push_back(y); }
+void Union(int x, int y) { par[x] = y; }
+int Find(int x, int c = 0) {
+    if(par[x] == x) return c ? -1 : x;
+    int p = Find(par[x], 1);
+    if(p == -1) return c ? par[x] : val[x];
+    if(sdom[val[x]] > sdom[val[par[x]]]) val[x] = val[par[x]];
+    par[x] = p;
+    return c ? p : val[x];
+}
+void dfs(int x) {
+    RS[ S[x] = ++cs ] = x;
+    par[cs] = sdom[cs] = val[cs] = cs;
+    for(int e : E[x]) {
+        if(S[e] == 0) dfs(e), rp[S[e]] = S[x];
+        RE[S[e]].push_back(S[x]);
+    }
+}
+int solve(int s, int *up) { // Calculate idoms
+    dfs(s);
+    for(int i=cs;i;i--) {
+        for(int e : RE[i]) sdom[i] = min(sdom[i], sdom[Find(e)]);
+        if(i > 1) rdom[sdom[i]].push_back(i);
+        for(int e : rdom[i]) {
+            int p = Find(e);
+            if(sdom[p] == i) dom[e] = i;
+            else dom[e] = p;
+        }
+        if(i > 1) Union(i, rp[i]);
+    }
+    for(int i=2;i<=cs;i++) if(sdom[i] != dom[i]) dom[i] = dom[dom[i]];
+    for(int i=2;i<=cs;i++) up[RS[i]] = RS[dom[i]];
+    return cs;
+}
+} // namespace dtree
+
+int par[N];
+dtree::add_edge(a, b); // a -> b
+int cnt = dtree::solve(s, par);
+// cnt : s에서 도달할 수 있는 정점, par: dominator tree의 par