BZOJ 1036 树的统计Count 树链剖分

题目大意：

给出一棵树, 3种操作

1.询问u到v路径上的最大点权

2.询问u到v路径上的点权和

3.修改i点权值为w

大致思路：

树链剖分练习题第5道...很水

树链剖分之后用线段树维护区间最大值和区间和即可, 单点修改区间查询

代码如下：

Result  :  Accepted     Memory  :  4356 KB     Time  :  2468 ms

/* * Author: Gatevin * Created Time:  2015/9/8 16:01:24 * File Name: Sakura_Chiyo.cpp */#include<iostream>#include<sstream>#include<fstream>#include<vector>#include<list>#include<deque>#include<queue>#include<stack>#include<map>#include<set>#include<bitset>#include<algorithm>#include<cstdio>#include<cstdlib>#include<cstring>#include<cctype>#include<cmath>#include<ctime>#include<iomanip>using namespace std;const double eps(1e-8);typedef long long lint;#define maxn 30010int top[maxn];int grandson[maxn];int dep[maxn];int siz[maxn];int belong[maxn];int father[maxn];int Q[maxn];int cnt;int hson[maxn];int n;bool vis[maxn];int id[maxn];int antiID[maxn];struct Edge{    int u, v, nex;    Edge(int _u, int _v, int _nex)    {        u = _u, v = _v, nex = _nex;    }    Edge(){}};int tot;int head[maxn];Edge edge[maxn << 1];void add_Edge(int x, int y){    edge[++tot] = Edge(x, y, head[x]);    head[x] = tot;}void split(){    cnt = 0;    int l = 0, r = 1;    dep[Q[r] = 1] = 1;    father[r] = -1;    while(l < r)    {        int x = Q[++l];        if(head[x] == -1) continue;        for(int j = head[x]; j + 1; j = edge[j].nex)        {            int y = edge[j].v;            if(y == father[x]) continue;            dep[Q[++r] = y] = dep[x] + 1;            father[y] = x;        }    }    for(int i = n; i; i--)    {        int x = Q[i], p = -1;        siz[x] = 1;        if(head[x] == -1) continue;        for(int j = head[x]; j + 1; j = edge[j].nex)        {            int y = edge[j].v;            if(y == father[x]) continue;            siz[x] += siz[y];            if(p == -1 || (p > 0  && siz[y] > siz[p]))                p = y;        }        if(p == -1)        {            hson[x] = -1;            grandson[++cnt] = x;            belong[top[cnt] = x] = cnt;        }        else        {            hson[x] = p;            belong[x] = belong[p];            top[belong[x]] = x;        }    }        int idx = 0;    memset(vis, 0, sizeof(vis));    for(int i = n; i; i--)    {        int x = Q[i];        if(vis[x]) continue;        vis[x] = 1;        id[x] = ++idx;        antiID[idx] = x;        while(father[x] != -1 && belong[father[x]] == belong[x] && !vis[father[x]])        {            x = father[x];            id[x] = ++idx;            antiID[idx] = x;            vis[x] = 1;        }    }    return;}int w[maxn];struct Segment_Tree{#define lson l, mid, rt << 1#define rson mid + 1, r, rt << 1 | 1    int sum[maxn << 2];    int ma[maxn << 2];    void pushUp(int rt)    {        sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];        ma[rt] = max(ma[rt << 1], ma[rt << 1 | 1]);        return;    }    void build(int l, int r, int rt)    {        if(l == r)        {            ma[rt] = sum[rt] = w[antiID[l]];            return;        }        int mid = (l + r) >> 1;        build(lson);        build(rson);        pushUp(rt);    }    void update(int l, int r, int rt, int pos, int value)    {        if(l == r)        {            ma[rt] = sum[rt] = value;            return;        }        int mid = (l + r) >> 1;        if(mid >= pos) update(lson, pos, value);        else update(rson, pos, value);        pushUp(rt);    }    int queryMax(int l, int r, int rt, int L, int R)    {        if(l >= L && r <= R)            return ma[rt];        int mid = (l + r) >> 1;        int ret = -1e9;        if(mid >= L) ret = max(ret, queryMax(lson, L, R));        if(mid + 1 <= R) ret = max(ret, queryMax(rson, L, R));        return ret;    }    int querySum(int l, int r, int rt, int L, int R)    {        if(l >= L && r <= R)            return sum[rt];        int mid = (l + r) >> 1;        int ret = 0;        if(mid >= L) ret += querySum(lson, L, R);        if(mid + 1 <= R) ret += querySum(rson, L, R);        return ret;    }};Segment_Tree st;int answerMax(int x, int y){    int ans = -1e9;    while(top[belong[x]] != top[belong[y]])    {        if(dep[top[belong[x]]] < dep[top[belong[y]]])            swap(x, y);        ans = max(ans, st.queryMax(1, n, 1, id[x], id[top[belong[x]]]));        x = father[top[belong[x]]];    }    if(dep[x] < dep[y]) swap(x, y);    ans = max(ans, st.queryMax(1, n, 1, id[x], id[y]));    return ans;}int answerSum(int x, int y){    int ans = 0;    while(top[belong[x]] != top[belong[y]])    {        if(dep[top[belong[x]]] < dep[top[belong[y]]])            swap(x, y);        ans += st.querySum(1, n, 1, id[x], id[top[belong[x]]]);        x = father[top[belong[x]]];    }    if(dep[x] < dep[y]) swap(x, y);    ans += st.querySum(1, n, 1, id[x], id[y]);    return ans;}int main(){    while(scanf("%d", &n) != EOF)    {        memset(head, -1, sizeof(head));        tot = 0;                int u, v, x;        for(int i = 1; i < n; i++)        {            scanf("%d %d", &u, &v);            add_Edge(u, v);            add_Edge(v, u);        }        for(int i = 1; i <= n; i++)            scanf("%d", w + i);        split();        st.build(1, n, 1);        int q;        scanf("%d", &q);        char op[10];        while(q--)        {            scanf("%s", op);            switch(op[0])            {                case 'C': scanf("%d %d", &u, &x);                          st.update(1, n, 1, id[u], x);                          break;                case 'Q': switch(op[1])                          {                              case 'M': scanf("%d %d", &u, &v);                                        printf("%d\n", answerMax(u, v));                                        break;                              case 'S': scanf("%d %d", &u, &v);                                        printf("%d\n", answerSum(u, v));                                        break;                          }                          break;            }        }    }    return 0;}