#1515. 【NOIP 十连测 Day 1】涂色 (colour)

https://sjzezoj.com/submission/60278

S2OJ/1515/1515.cpp

@@ -0,0 +1,127 @@
+#include <iostream>
+#include <algorithm>
+#include <tuple>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 5e5 + 5;
+
+int n, m, cnt, father[N];
+int dep[N], id[N], siz[N], fa[N], son[N], top[N], w[N];
+std::tuple<int, int, bool, int> edges[N];
+std::vector<std::pair<int, int>> g[N];
+
+void dfs1(int u, int f) {
+    fa[u] = father[u] = f;
+    dep[u] = dep[f] + 1;
+    siz[u] = 1;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            i = e.second;
+
+        if (v == f) continue;
+
+        id[v] = i;
+        dfs1(v, u);
+        siz[u] += siz[v];
+
+        if (siz[son[u]] < siz[v]) son[u] = v;
+    }
+}
+
+void dfs2(int u, int t) {
+    top[u] = t;
+
+    if (!son[u]) return;
+
+    dfs2(son[u], t);
+
+    for (auto e : g[u]) {
+        int v = e.first;
+
+        if (v == fa[u]) continue;
+        if (v == son[u]) continue;
+
+        dfs2(v, v);
+    }
+}
+
+int lca(int u, int v) {
+    while (top[u] != top[v]) {
+        if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
+        u = fa[top[u]];
+    }
+    return dep[u] < dep[v] ? u : v;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1, u, v, c; i <= m; i++) {
+        cin >> u >> v >> c;
+
+        if (c) {
+            g[u].emplace_back(v, i);
+            g[v].emplace_back(u, i);
+        }
+
+        edges[i] = std::make_tuple(u, v, c, 0);
+    }
+
+    dfs1(1, 1);
+    dfs2(1, 1);
+
+    for (int i = 1; i <= m; i++) {
+        if (std::get<3>(edges[i])) continue;
+
+        if (!std::get<2>(edges[i])) {
+            int u = std::get<0>(edges[i]),
+                v = std::get<1>(edges[i]),
+                l = lca(u, v);
+            std::vector<int> ids;
+
+            while (dep[u] > dep[l]) {
+                if (!std::get<3>(edges[id[u]])) {
+                    ids.push_back(id[u]);
+                }
+
+                int t = father[u];
+                father[u] = l;
+                u = t;
+            }
+
+            while (dep[v] > dep[l]) {
+                if (!std::get<3>(edges[id[v]])) {
+                    ids.push_back(id[v]);
+                }
+
+                int t = father[v];
+                father[v] = l;
+                v = t;
+            }
+
+            std::sort(ids.begin(), ids.end());
+
+            for (int id : ids) {
+                std::get<3>(edges[id]) = ++cnt;
+            }
+        }
+
+        std::get<3>(edges[i]) = ++cnt;
+    }
+
+    for (int i = 1; i <= m; i++) {
+        cout << std::get<3>(edges[i]) << ' ';
+    }
+
+    cout << endl;
+
+    return 0;
+}