Aragorn's Story HDU

树链剖分模板题目。

树链剖分，就是先选定好根节点，由根节点往下，沿着子树节点最多的节点往下，将其拆成链，再由链组成线段树的数据结构

#pragma comment(linker,"/STACK:100000000,100000000")#include <iostream>#include <stdio.h>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 50010;struct Edge{    int to, next;};int n, m, Q;Edge edge[2*MAXN];int head[MAXN], tot;int top[MAXN];//每个节点所在链的头节点的位置int fa[MAXN];//每个节点的父亲节点int deep[MAXN];//每个节点的深度int num[MAXN];//以第i个节点为根节点时子节点的个数int p[MAXN];//i节点在线段树的位置int fp[MAXN];//p的反函数int son[MAXN];//每个节点的最大分支的儿子节点int a[MAXN];int pos;void init(){    tot = 0;    memset(head, -1, sizeof(head));    pos = 1;    memset(son, -1, sizeof(son));}void addedge(int u, int v){    edge[tot].to = v; edge[tot].next = head[u];    head[u] = tot++;}void dfs1(int u, int father ,int dep){    deep[u] = dep;    fa[u] = father;    num[u] = 1;    for (int i = head[u]; ~i; i = edge[i].next) {        int v = edge[i].to;        if (v != father) {            dfs1(v, u, dep+1);            num[u] += num[v];            if (son[u] == -1 || num[v] > num[son[u]])                son[u] = v;        }       }}void getpos(int u, int sp){    top[u] = sp;    p[u] = pos++;    fp[p[u]] = u;    if (son[u] == -1) return;    getpos(son[u], sp);    for (int i = head[u]; ~i; i = edge[i].next) {        int v = edge[i].to;        if (v != fa[u] && v != son[u]) {            getpos(v, v);        }    }}#define lson o<<1,l,mid#define rson o<<1|1,mid+1,rint sum[MAXN<<2];void build(int o, int l, int r) {    if (l == r) { sum[o] = a[fp[l]]; return; }    int mid = (l+r) >> 1;    build(lson); build(rson);    sum[o] = 0;}void pushdown(int o) {    if (sum[o]) {        sum[o<<1] += sum[o];        sum[o<<1|1] += sum[o];        sum[o] = 0;    }}int query(int o, int l, int r, int v) {    if (l == r) return sum[o];    pushdown(o);    int mid = (l+r) >> 1;    if (v <= mid) return query(lson, v);    return query(rson, v);}void update(int o, int l, int r, int L, int R, int v) {    if (l >= L && r <= R) { sum[o] += v; return ; }    pushdown(o);    int mid = (l+r) >> 1;    if (L <= mid) update(lson, L, R, v);    if (R > mid) update(rson, L, R, v);}void change(int x, int y, int w, int n) {    while (top[x] != top[y]) {        if (deep[top[x]] < deep[top[y]]) swap(x, y);        update(1, 1, n, p[top[x]], p[x], w);        x = fa[top[x]];    }    if (deep[x] > deep[y]) swap(x, y);    update(1, 1, n, p[x], p[y], w);}char buf[5];int x, y, z;int main(){    while (scanf("%d%d%d" , &n, &m, &Q) != EOF) {        for (int i = 1; i <= n; i++)             scanf("%d", a+i);        init();        for (int i = 1; i <= m; i++) {            scanf("%d%d", &x, &y);            addedge(x, y);            addedge(y, x);        }        dfs1(1, 0, 0);        getpos(1, 1);        build(1, 1, n);        for (int i = 1; i <= Q; i++) {            scanf("%s", buf);            if (buf[0] == 'Q') {                scanf("%d", &x);                printf("%d\n", query(1, 1, n, p[x]));            }            else {                scanf("%d%d%d", &x, &y, &z);                if (buf[0] == 'D') z = -z;                change(x, y, z, n);            }        }    }    return 0;}