标签:style http color io os ar for sp c
就树链剖分,线段树维护sum和maxx即可
代码:
#include <cstdio> #include <cstring> #include <vector> #include <algorithm> using namespace std; const int N = 30005; int dep[N], fa[N], son[N], sz[N], top[N], id[N], idx, val[N]; int first[N], next[N * 2], vv[N * 2], en; void init() { en = 0; idx = 0; memset(first, -1, sizeof(first)); } void add_Edge(int u, int v) { vv[en] = v; next[en] = first[u]; first[u] = en++; } void dfs1(int u, int f, int d) { dep[u] = d; sz[u] = 1; fa[u] = f; son[u] = 0; for (int i = first[u]; i + 1; i = next[i]) { int v = vv[i]; if (v == f) continue; dfs1(v, u, d + 1); sz[u] += sz[v]; if (sz[son[u]] < sz[v]) son[u] = v; } } void dfs2(int u, int tp) { id[u] = ++idx; top[u] = tp; if (son[u]) dfs2(son[u], tp); for (int i = first[u]; i + 1; i = next[i]) { int v = vv[i]; if (v == fa[u] || v == son[u]) continue; dfs2(v, v); } } const int INF = 0x3f3f3f3f; int n; #define lson(x) ((x<<1)+1) #define rson(x) ((x<<1)+2) struct Node { int l, r, maxx, sum; } node[N * 4]; void pushup(int x) { node[x].maxx = max(node[lson(x)].maxx, node[rson(x)].maxx); node[x].sum = node[lson(x)].sum + node[rson(x)].sum; } void build(int l, int r, int x = 0) { node[x].l = l; node[x].r = r; if (l == r) { node[x].maxx = node[x].sum = val[l]; return; } int mid = (l + r) / 2; build(l, mid, lson(x)); build(mid + 1, r, rson(x)); pushup(x); } void add(int v, int val, int x = 0) { if (node[x].l == node[x].r) { node[x].sum = node[x].maxx = val; return; } int mid = (node[x].l + node[x].r) / 2; if (v <= mid) add(v, val, lson(x)); if (v > mid) add(v, val, rson(x)); pushup(x); } int query(int l, int r, int ty, int x = 0) { if (node[x].l >= l && node[x].r <= r) { if (ty) return node[x].sum; return node[x].maxx; } int mid = (node[x].l + node[x].r) / 2; int ans = -INF, tmp; if (ty) ans = 0; if (l <= mid) { tmp = query(l, r, ty, lson(x)); if (ty) ans += tmp; else ans = max(ans, tmp); } if (r > mid) { tmp = query(l, r, ty, rson(x)); if (ty) ans += tmp; else ans = max(ans, tmp); } return ans; } int gao(int u, int v, int ty) { int ans = -INF, tmp; if (ty) ans = 0; int tp1 = top[u], tp2 = top[v]; while (tp1 != tp2) { if (dep[tp1] < dep[tp2]) { swap(tp1, tp2); swap(u, v); } tmp = query(id[tp1], id[u], ty); if (ty) ans += tmp; else ans = max(ans, tmp); u = fa[tp1]; tp1 = top[u]; } if (dep[u] > dep[v]) swap(u, v); tmp = query(id[u], id[v], ty); if (ty) ans += tmp; else ans = max(ans, tmp); return ans; } int main() { while (~scanf("%d", &n)) { init(); int u, v; for (int i = 1; i < n; i++) { scanf("%d%d", &u, &v); add_Edge(u, v); add_Edge(v, u); } dfs1(1, 0, 1); dfs2(1, 1); for (int i = 1; i <= n; i++) scanf("%d", &val[id[i]]); build(1, idx); int q; char Q[10]; int a, b; scanf("%d", &q); while (q--) { scanf("%s%d%d", Q, &a, &b); if (Q[0] == 'C') add(id[a], b); else { int ty = 0; if (Q[1] == 'S') ty = 1; printf("%d\n", gao(a, b, ty)); } } } return 0; }
标签:style http color io os ar for sp c
原文地址:http://blog.csdn.net/accelerator_/article/details/39706219