[模板]BZOJ4756線段樹合並
阿新 • • 發佈：2019-02-20
線段樹合並 sdi size zoj https algo edge oid right
題面
Solution:
板子不解釋
#include <iostream> #include <algorithm> #include <cstdio> #include <cstring> using namespace std; namespace io { char buf[1<<21], *pos = buf, *end = buf; inline char getc() { return pos == end && (end = (pos = buf) + fread(buf, 1, 1<<21, stdin), pos == end) ? EOF : *pos ++; } inline int rint() { register int x = 0, f = 1; register char c; while (!isdigit(c = getc())) if (c == '-') f = -1; while (x = (x << 1) + (x << 3) + (c ^ 48), isdigit(c = getc())); return x * f; } } using io::rint; const int N = 1e5 + 1; int n, ans[N]; int Ht[N], a[N], SIZE; int size[N<<6], rt[N], cnt, ls[N<<6], rs[N<<6];//線段樹合並一般<<6位 int head[N], nxt[N<<1], ver[N<<1], tot; void addEdge(int u, int v) { ver[++tot] = v, nxt[tot] = head[u], head[u] = tot; } void pushup(int x) { size[x] = size[ls[x]] + size[rs[x]]; } void insert(int &x, int lval, int rval, int val) { x = ++cnt; if (lval == rval) { size[x] ++; return; } int mid = lval + rval >> 1; if (val <= mid) insert(ls[x], lval, mid, val); else insert(rs[x], mid+1, rval, val); pushup(x); } int query(int x, int lval, int rval, int Left, int Right) { if (!x) return 0; if (Left <= lval && rval <= Right) return size[x]; int mid = lval + rval >> 1; int sum = 0; if (Left <= mid) sum += query(ls[x], lval, mid, Left, Right); if (mid < Right) sum += query(rs[x], mid + 1, rval, Left, Right); return sum; } int merge(int x, int y) { if ((!x) || (!y)) return x + y; ls[x] = merge(ls[x], ls[y]); rs[x] = merge(rs[x], rs[y]); pushup(x); return x; } void DFS(int u, int fa) { insert(rt[u], 1, SIZE, a[u]); for (int i = head[u]; i; i = nxt[i]) if (ver[i] != fa) DFS(ver[i], u); for (int i = head[u]; i; i = nxt[i]) if (ver[i] != fa) rt[u] = merge(rt[u], rt[ver[i]]); ans[u] = query(rt[u], 1, SIZE, a[u]+1, SIZE); } int main() { freopen("BZOJ4756.in", "r", stdin); freopen("BZOJ4756.out", "w", stdout); n = rint(); for (int i = 1; i <= n; ++ i) a[i] = Ht[i] = rint(); for (int i = 2; i <= n; ++ i) { int fa = rint(); addEdge(fa, i); addEdge(i, fa); } sort(Ht + 1, Ht + 1 + n); SIZE = unique(Ht + 1, Ht + 1 + n) - Ht - 1; for (int i = 1; i <= n; ++ i) a[i] = lower_bound(Ht + 1, Ht + 1 + n, a[i]) - Ht; DFS(1,0); for (int i = 1; i <= n; ++ i) printf("%d\n", ans[i]); }
[模板]BZOJ4756線段樹合並