2325: [ZJOI2011]道馆之战

/*
Author:wuhuajun
*/
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define lson l, mid, rt << 1
#define rson mid+1, r, rt << 1 | 1
using namespace std;
 
typedef long long ll;
typedef double dd;
const int maxn=100010, INF = 1000000007;
 
int edge, n, fa[maxn], sz[maxn], son[maxn], dep[maxn], hash[maxn], top[maxn];
int h[maxn], num, a[maxn], x, y, tx, ty, Q, b[maxn];
char s[22], s1[22], s2[22];
 
struct Edge
{
    int to, ne;
} e[maxn * 2];
 
struct Seg
{
    int x[2][2], l[2], r[2];
    void clear()
    {
        x[0][0] = x[0][1] = x[1][0] = x[1][1] = 0;
        l[0] = l[1] = r[0] = r[1] = 0;
    }
} seg[maxn << 2], ans, c, L, R, ret;
 
void close()
{
    exit(0);
}
 
void addedge(int x,int y)
{
    e[edge].to = y;
    e[edge].ne = h[x];
    h[x] = edge++;
}
 
void dfs(int k,int from)
{
    sz[k] = 1;
    son[k] = 0;
    dep[k] = dep[from] + 1;
    for (int p=h[k];p!=-1;p=e[p].ne)
    {
        int to = e[p].to;
        if (from == to) continue;
        fa[to] = k;
        dfs(to, k);
        sz[k] += sz[to];
        if (sz[to] > sz[son[k]]) son[k] = to;
    }
}
 
void build(int k,int from)
{
    hash[k] = ++num;
    top[k] = from;
    if (son[k]) build(son[k], from);
    for (int p=h[k];p!=-1;p=e[p].ne)
    {
        int to = e[p].to;
        if (to != fa[k] && to != son[k])
            build(to, to);
    }
}
 
//{{{Segment部分
 
int cal(int x,int y)
{
    return max(-INF, max(x, y));
}
 
Seg operator + (Seg a,Seg b)
{
    if (a.x[0][0] == 0 && a.x[0][1] == 0 && a.x[1][0] == 0 && a.x[1][1] == 0 && a.l[0] == 0 && a.l[1] == 0 && a.r[0] == 0 && a.r[1] == 0)
        return b;
    if (b.x[0][0] == 0 && b.x[0][1] == 0 && b.x[1][0] == 0 && b.x[1][1] == 0 && b.l[0] == 0 && b.l[1] == 0 && b.r[0] == 0 && b.r[1] == 0)
        return a;
    c.x[0][0] = cal(a.x[0][0] + b.x[0][0], a.x[0][1] + b.x[1][0]);
    c.x[0][1] = cal(a.x[0][0] + b.x[0][1], a.x[0][1] + b.x[1][1]);
    c.x[1][0] = cal(a.x[1][0] + b.x[0][0], a.x[1][1] + b.x[1][0]);
    c.x[1][1] = cal(a.x[1][0] + b.x[0][1], a.x[1][1] + b.x[1][1]);
    c.l[0] = max(a.l[0], max(a.x[0][0] + b.l[0], a.x[0][1] + b.l[1]));
    c.l[1] = max(a.l[1], max(a.x[1][0] + b.l[0], a.x[1][1] + b.l[1]));
    c.r[0] = max(b.r[0], max(b.x[0][0] + a.r[0], b.x[1][0] + a.r[1]));
    c.r[1] = max(b.r[1], max(b.x[0][1] + a.r[0], b.x[1][1] + a.r[1]));
    return c;
}
 
void change(int L,int R,int val1,int val2,int l,int r,int rt)
{
    if (L <= l && r <= R)
    {
        seg[rt].x[0][0] = seg[rt].l[0] = seg[rt].r[0] = val1;
        seg[rt].x[1][1] = seg[rt].l[1] = seg[rt].r[1] = val2;
        if (val1 == 1 && val2 == 1)
        {
            seg[rt].l[0] = seg[rt].l[1] = seg[rt].r[0] = seg[rt].r[1] = 2;
            seg[rt].x[0][1] = seg[rt].x[1][0] = 2;
        }
        else
        {
            seg[rt].x[0][1] = seg[rt].x[1][0] = -INF;
        }
        seg[rt].l[0] = max(seg[rt].l[0], 0);
        seg[rt].l[1] = max(seg[rt].l[1], 0);
        seg[rt].r[0] = max(seg[rt].r[0], 0);
        seg[rt].r[1] = max(seg[rt].r[1], 0);
        return;
    }
    int mid = (l + r) >> 1;
    if (L <= mid)
        change(L,R,val1,val2,lson);
    if (mid + 1 <= R)
        change(L,R,val1,val2,rson);
    seg[rt] = seg[rt << 1] + seg[rt << 1 | 1];
}
 
Seg query(int L,int R,int l,int r,int rt)
{
    if (L <= l && r <= R)
    {
        return seg[rt];
    }
    int mid = (l + r) >> 1;
    Seg ans;
    ans.clear();
    if (L <= mid)
        ans = ans + query(L,R,lson);
    if (mid + 1 <= R)
        ans = ans + query(L,R,rson);
    return ans;
}
//}}}
 
Seg get_ans()
{
    tx = top[x];
    ty = top[y];
    L.clear();
    R.clear();
    while (tx != ty)
    {
        if (dep[tx] < dep[ty])
        {
            R = query(hash[ty], hash[y], 1, n, 1) + R;
            y = fa[ty];
            ty = top[y];
        }
        else
        {
            L = query(hash[tx], hash[x], 1, n, 1) + L;
            x = fa[tx];
            tx = top[x];
        }
    }
    if (dep[x] < dep[y])
    {
        R = query(hash[x], hash[y], 1, n, 1) + R;
    }
    else
    {
        L = query(hash[y], hash[x], 1, n, 1) + L;
    }
    swap(L.x[0][1], L.x[1][0]);
    swap(L.l[0], L.r[0]);
    swap(L.l[1], L.r[1]);
    return L + R;
}
 
void init()
{
    scanf("%d %d",&n,&Q);
    memset(h,-1,sizeof(h));
    for (int i=1;i<=n-1;i++)
    {
        scanf("%d %d",&x, &y);
        addedge(x, y);
        addedge(y, x);
    }
    for (int i=1;i<=n;i++)
    {
        scanf("%s", s1);
        a[i] = s1[0] == ‘.‘ ? 1 : -INF;
        b[i] = s1[1] == ‘.‘ ? 1 : -INF;
    }
    dfs(1, 0);
    build(1, 1);
    /*
    for (int i=1;i<=n;i++)
    {
        printf("i:%d top:%d hash:%d\n",i, top[i], hash[i]);
    }
    */
    for (int i=1;i<=n;i++)
        change(hash[i], hash[i], a[i], b[i], 1, n, 1);
    while (Q--)
    {
        scanf("%s", s);
        if (s[0] == ‘Q‘)
        {
            scanf("%d %d",&x, &y);
            ret = get_ans();
            printf("%d\n", max(ret.l[0], ret.l[1]));
        }
        else
        {
            scanf("%d",&x);
            scanf("%s", s1);
            int t1 = s1[0] == ‘.‘ ? 1 : -INF;
            int t2 = s1[1] == ‘.‘ ? 1 : -INF;
            change(hash[x], hash[x], t1, t2, 1, n, 1);
        }
    }
}
 
int main ()
{
    init();
    close();
    return 0;
}