3 条题解
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将询问离线下来,按右端点排序,用 LCT 维护割边并用树状数组查询即可。
#include <bits/stdc++.h> using namespace std; inline int read() { int x = 0, f = 0; char ch = getchar(); while (ch < '0' or ch > '9') f |= (ch == '-'), ch = getchar(); while (ch >= '0' and ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar(); return f ? -x : x; } int __stk[128], __top; inline void write(int x) { if(x < 0) putchar('-'), x = -x; do { __stk[++__top] = x % 10, x /= 10; } while (x); while (__top) putchar(__stk[__top--] + '0'); } const int mod = 998244353; void Min(int &x, int y) { y < x and (x = y); } void Max(int &x, int y) { y > x and (x = y); } void inc(int &x, int y) { (x += y) >= mod and (x -= mod); } void mul(int &x, int y) { x = 1ll * x * y % mod; } int q_pow(int x, int k) { int res = 1; for (; k; k >>= 1, mul(x, x)) if (k & 1) mul(res, x); return res; } bool stmer; const int N = 4e5 + 10; struct edge { int u, v; } e[N]; struct Query { int l, id; }; int n, m, q; int ans[N]; vector<Query> op[N]; namespace BIT { int t[N]; void add(int x, int k) { while (x) t[x] += k, x -= x & -x; } int ask(int x) { int res = 0; while (x <= m) res += t[x], x += x & -x; return res; } } namespace LCT { int top; int fa[N], t[N][2], a[N], s[N], tag[N]; int stk[N]; bool nrt(int x) { return t[fa[x]][0] == x or t[fa[x]][1] == x; } int get(int x) { return t[fa[x]][1] == x; } void reverse(int x) { swap(t[x][0], t[x][1]), tag[x] ^= 1; } void pushdown(int x) { if (tag[x]) reverse(t[x][0]), reverse(t[x][1]), tag[x] = 0; } void update(int x) { s[x] = min({ s[t[x][0]], s[t[x][1]], a[x] }); } void rotate(int x) { int f1 = fa[x], f2 = fa[f1], k = get(x); if (nrt(f1)) t[f2][get(f1)] = x; fa[x] = f2; t[f1][k] = t[x][!k], fa[t[f1][k]] = f1; t[x][!k] = f1, fa[f1] = x; update(f1), update(x); } void splay(int x) { int p = stk[++top] = x; while (nrt(p)) stk[++top] = p = fa[p]; while (top) pushdown(stk[top--]); for (int f = fa[x]; nrt(x); rotate(x), f = fa[x]) if (nrt(f)) rotate(get(x) == get(f) ? f : x); } void access(int x) { int f = 0; while (x) splay(x), t[x][1] = f, update(x), f = x, x = fa[x]; } void mkrt(int x) { access(x), splay(x), reverse(x); } void split(int u, int v) { mkrt(u), access(v), splay(v); } int findrt(int x) { access(x), splay(x); while (t[x][0]) pushdown(x), x = t[x][0]; splay(x); return x; } void link(int u, int v) { mkrt(u), fa[u] = v; } void cut(int u, int v) { split(u, v), fa[u] = t[v][0] = 0, update(v); } bool check(int u, int v) { mkrt(u); return findrt(v) == u; } void init() { for (int i = 0; i <= n + m; i++) { fa[i] = t[i][0] = t[i][1] = BIT :: t[i] = 0; s[i] = a[i] = i <= n ? n + m + 1 : i; } } } void solve() { n = read(), m = read(), q = read(), LCT :: init(); for (int i = 1; i <= m; i++) e[i] = { read(), read() }; for (int i = 1; i <= q; i++) { int l = read(), r = read(); op[r].push_back({ l, i }); } for (int i = 1; i <= m; i++) { int u = e[i].u, v = e[i].v; if (LCT :: check(u, v) and u != v) { LCT :: split(u, v); int x = LCT :: s[v] - n; BIT :: add(x, -1); LCT :: cut(e[x].u, x + n), LCT :: cut(e[x].v, x + n); } if (u ^ v) { BIT :: add(i, 1); LCT :: link(u, i + n); LCT :: link(i + n, v); } for (Query l : op[i]) ans[l.id] = n - BIT :: ask(l.l); op[i].clear(); } for (int i = 1; i <= q; i++) write(ans[i]), putchar('\n'); } bool edmer; signed main() { // freopen("A.in", "r", stdin); // freopen("A.out", "w", stdout); cerr << "[Memory] " << (&stmer - &edmer) / 1024 / 1024 << " MB\n"; int T = 1; while(T--) solve(); cerr << "[Runtime] " << (double) clock() / CLOCKS_PER_SEC << " seconds\n"; return 0; }
信息
- ID
- 134
- 时间
- 100ms
- 内存
- 256MiB
- 难度
- 10
- 标签
- 递交数
- 37
- 已通过
- 4
- 上传者