|BZOJ 1036|树链剖分|线段树|[ZJOI2008]树的统计Count

bzoj 1036

树剖+线段树。

第一个树剖题，终于AC

#include<cstdio>#include<cstring>#include<algorithm>#include<vector>#define fo(i, j, k) for (i=(j);i<=(k);i++)#define fd(i, k, j) for (i=(k);i>=(j);i--)#define rd(a) scanf("%d", &a)#define rd2(a, b) scanf("%d%d", &a, &b)#define rd3(a, b, c) scanf("%d%d%d", &a, &b, &c)#define ms(i, j) memset(i, j, sizeof i)#define FN2 "bzoj1036" using namespace std;const int MAXN = 30000 + 5;int dep[MAXN], son[MAXN], fa[MAXN], siz[MAXN]; //深度，重儿子，父亲，子树大小 int p[MAXN], top[MAXN], pre; //在线段树中的位置，所在重链顶部，线段树当前标号 int n, wi[MAXN];vector<int> G[MAXN];void dfs1(int u, int f)//第一次dfs记录值 {    int i;    dep[u] = dep[f] + 1, fa[u] = f, siz[u] = 1;    fo (i, 0, G[u].size()-1) {        int v = G[u][i];        if (v!=f) {            dfs1(v, u);            siz[u] += siz[v];            if (son[u]==-1||siz[son[u]]<siz[v]) son[u] = v;        }    }}void dfs2(int u, int chain) {//第二次dfs连重儿子成重链     int i;     p[u] = ++pre, top[u] = chain;    if (son[u]!=-1) {        dfs2(son[u], chain);        fo (i, 0, G[u].size()-1) {            int v = G[u][i];            if (v!=son[u]&&v!=fa[u]) dfs2(v, v);        }    }}int maxv[MAXN*4], sumv[MAXN*4];void pushup(int o) {    int lc = o*2, rc = o*2+1;    maxv[o] = max(maxv[lc], maxv[rc]);    sumv[o] = sumv[lc] + sumv[rc];}void update(int o, int l, int r, int p, int v) {    int lc = o*2, rc = o*2+1, M = (l+r)/2;    if (l==r) {        sumv[o] = maxv[o] = v; return ;    }    if (p<=M) update(lc, l, M, p, v); else if (M<p) update(rc, M+1, r, p, v);    pushup(o);}int getMax(int o, int l, int r, int x, int y) {    int lc = o*2, rc = o*2+1, M = (l+r)/2, ret = -200000000;    if (x<=l&&r<=y) {        return maxv[o];    }    if (x<=M) ret = max(ret, getMax(lc, l, M, x, y));    if (M<y)  ret = max(ret, getMax(rc, M+1, r, x, y));     return ret;}int getSum(int o, int l, int r, int x, int y) {    int lc = o*2, rc = o*2+1, M = (l+r)/2, ret = 0;    if (x<=l&&r<=y) {        return sumv[o];    }    if (x<=M) ret += getSum(lc, l, M, x, y);    if (M<y)  ret += getSum(rc, M+1, r, x, y);      return ret;}int findMax(int u, int v){    int f1 = top[u], f2 = top[v];    int ret = -200000000;    while (f1!=f2) {        if (dep[f1]<dep[f2]) swap(f1, f2), swap(u, v);        ret = max(ret, getMax(1, 1, n, p[f1], p[u]));        u = fa[f1], f1 = top[u];    }       if (dep[u]<dep[v]) swap(u, v);    return max(ret, getMax(1, 1, n, p[v], p[u]));}int findSum(int u, int v){    int f1 = top[u], f2 = top[v];    int ret = 0;    while (f1!=f2) {        if (dep[f1]<dep[f2]) swap(f1, f2), swap(u, v);        ret += getSum(1, 1, n, p[f1], p[u]);        u = fa[f1], f1 = top[u];    }       if (dep[u]<dep[v]) swap(u, v);    return ret+getSum(1, 1, n, p[v], p[u]);}void init() {    int i; pre = 0;    fo (i, 1, n) dep[i] = fa[i] = siz[i] = p[i] = top[i] = 0, son[i] = -1, G[i].clear();    fo (i, 1, n*4) maxv[i] = -200000000, sumv[i] = 0;    fo (i, 1, n-1) {        int a, b; rd2(a, b);        G[a].push_back(b), G[b].push_back(a);    }}void solve() {    int q, i;     dfs1(1, 0);    dfs2(1, 1);    fo (i, 1, n) rd(wi[i]), update(1, 1, n, p[i], wi[i]);     rd(q);    fo (i, 1, q) {        char ch[10]; scanf("%s", ch);        if (ch[0]=='C') {            int u, t; rd2(u, t), update(1, 1, n, p[u], t);        } else if (ch[1]=='M') {            int u, v; rd2(u, v), printf("%d\n", findMax(u, v));        } else if (ch[1]=='S') {            int u, v; rd2(u, v), printf("%d\n", findSum(u, v));        }    }}int main() {    #ifndef ONLINE_JUDGE    freopen(FN2".in","r",stdin);freopen(FN2".out","w",stdout);    #endif    while (rd(n)==1) init(), solve();    return 0;}