G - Shortest Path Queries

https://codeforces.com/contest/938/submission/192331445

Codeforces/938/G/G.cpp

@@ -0,0 +1,218 @@
+#include <iostream>
+#include <algorithm>
+#include <iterator>
+#include <map>
+#include <stack>
+#include <utility>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int n, m, q;
+int cnt = 1, edge_cnt;
+std::map<int, int> map[N];
+std::vector<std::pair<int, int>> qs[N];
+std::vector<int> ans;
+
+struct edge {
+    int l, r, x, y, w;
+
+    edge(const int &_x = 0,
+         const int &_y = 0,
+         const int &_l = 0,
+         const int &_w = 0)
+        : l(_l), r(0), x(_x), y(_y), w(_w) {}
+} edges[N << 1];
+
+struct dsu_item {
+    int f, w, s;
+
+    dsu_item(const int &_f = 0, const int &_w = 0)
+        : f(_f), w(_w), s(1) {}
+} dsu[N];
+
+struct seg_node : std::vector<edge> {
+    int l, r;
+
+    seg_node(const int &_l = 0,
+             const int &_r = 0,
+             const std::vector<edge> &_v = std::vector<edge>())
+        : std::vector<edge>(_v), l(_l), r(_r) {}
+} tr[N << 2];
+
+class liner_base {
+  private:
+    int b[31];
+
+  public:
+    void insert(int w) {
+        for (int i = 29; i >= 0; --i) {
+            if (!(w >> i)) continue;
+
+            if (!b[i]) {
+                b[i] = w;
+
+                break;
+            }
+
+            w ^= b[i];
+        }
+    }
+
+    int query(int w) {
+        for (int i = 29; i >= 0; --i) {
+            if (!((w >> i) & 1)) continue;
+
+            w ^= b[i];
+        }
+
+        return w;
+    }
+} lb[std::__lg(N << 2) + 1];
+
+int find(int x, int &w) {
+    while (x != dsu[x].f) {
+        w ^= dsu[x].w;
+        x = dsu[x].f;
+    }
+
+    return x;
+}
+
+void merge(int x, int y, int w, int d) {
+    if (x == y) {
+        lb[d].insert(w);
+
+        return;
+    }
+
+    if (dsu[x].s < dsu[y].s) std::swap(x, y);
+
+    dsu[y].f = x;
+    dsu[y].w = w;
+    dsu[x].s += dsu[y].s;
+}
+
+int query(int x, int y, int d) {
+    int w = 0;
+
+    x = find(x, w);
+    y = find(y, w);
+
+    if (x != y) return -1;
+
+    return lb[d].query(w);
+}
+
+void build(int u, int l, int r) {
+    tr[u] = seg_node(l, r);
+
+    if (l == r) return;
+
+    int mid = (l + r) >> 1;
+
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+}
+
+void insert(int u, const edge &e) {
+    if (e.l <= tr[u].l && tr[u].r <= e.r) {
+        tr[u].emplace_back(e);
+
+        return;
+    }
+
+    int mid = (tr[u].l + tr[u].r) >> 1;
+
+    if (e.l <= mid) insert(u << 1, e);
+    if (e.r > mid) insert(u << 1 | 1, e);
+}
+
+void solve(int u, int l, int r, int d) {
+    std::stack<std::pair<int, dsu_item>> st;
+
+    lb[d] = lb[d - 1];
+
+    for (auto e : tr[u]) {
+        int wx = 0, wy = 0;
+        int x = find(e.x, wx);
+        int y = find(e.y, wy);
+
+        st.emplace(x, dsu[x]);
+        st.emplace(y, dsu[y]);
+
+        merge(x, y, wx ^ wy ^ e.w, d);
+    }
+
+    if (l == r) {
+        for (auto o : qs[l]) {
+            ans.emplace_back(query(o.first, o.second, d));
+        }
+    } else {
+        int mid = (l + r) >> 1;
+
+        solve(u << 1, l, mid, d + 1);
+        solve(u << 1 | 1, mid + 1, r, d + 1);
+    }
+
+    while (!st.empty()) {
+        dsu[st.top().first] = st.top().second;
+        st.pop();
+    }
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1; i <= n; i++) {
+        dsu[i] = dsu_item(i, 0);
+    }
+
+    for (int i = 1, x, y, d; i <= m; i++) {
+        cin >> x >> y >> d;
+
+        map[x][y] = map[y][x] = ++edge_cnt;
+
+        edges[edge_cnt] = edge(x, y, 1, d);
+    }
+
+    cin >> q;
+
+    for (int i = 1, op, x, y; i <= q; i++) {
+        cin >> op >> x >> y;
+
+        if (op == 1) {
+            int d;
+
+            cin >> d;
+
+            map[x][y] = map[y][x] = ++edge_cnt;
+            edges[edge_cnt] = edge(x, y, ++cnt, d);
+        } else if (op == 2) {
+            edges[map[x][y]].r = cnt++;
+        } else {  // op == 3
+            qs[cnt].emplace_back(x, y);
+        }
+    }
+
+    build(1, 1, cnt);
+
+    for (int i = 1; i <= edge_cnt; i++) {
+        if (!edges[i].r) edges[i].r = cnt;
+
+        insert(1, edges[i]);
+    }
+
+    solve(1, 1, cnt, 1);
+
+    std::copy(ans.begin(), ans.end(), std::ostream_iterator<int>(cout, "\n"));
+
+    return 0;
+}