BZOJ2243 [SDOI2011]染色（树链剖分+线段树合并）

题目链接 BZOJ2243

树链剖分 $+$ 线段树

线段树每个节点维护$lc$, $rc$, $s$

$lc$代表该区间的最左端的颜色，$rc$代表该区间的最右端的颜色

$s$代表该区间的所有连续颜色段数（仅考虑该区间）

$lazy$表示延迟信息。

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#include <bits/stdc++.h>   using namespace std;   #define rep(i, a, b)    for (int i(a); i <= (b); ++i) #define dec(i, a, b)    for (int i(a); i >= (b); --i) #define lson        i << 1, L, mid #define rson        i << 1 | 1, mid + 1, R   typedef long long LL;   const int N = 1e5 + 10; const int A = 21;   vector <int> v[N]; int n, m; int c[N]; int f[N][A]; int lazy[N << 2], s[N << 2], lc[N << 2], rc[N << 2]; int h[N], deep[N], sz[N]; int son[N]; int tot = 0; int top[N];     int LCA(int a, int b){     if (deep[a] < deep[b]) swap(a, b);     for (int i = 0,  delta = deep[a] - deep[b]; delta; delta >>= 1, ++i) if (delta & 1) a = f[a][i];     if (a == b) return a;     dec(i, 19, 0) if (f[a][i] != f[b][i]) a = f[a][i], b = f[b][i];     return f[a][0]; }   inline void pushup(int i){     lc[i] = lc[i << 1];     rc[i] = rc[i << 1 | 1];     if (rc[i << 1] ^ lc[i << 1 | 1]) s[i] = s[i << 1] + s[i << 1 | 1];     else s[i] = s[i << 1] + s[i << 1 | 1] - 1; }   inline void pushdown(int i, int L, int R){     int tmp = lazy[i];     if (tmp == -1 || L == R) return;       s[i << 1]      = s[i << 1 | 1]    = 1;     lazy[i << 1]   = lazy[i << 1 | 1] = tmp;       lc[i << 1]     = rc[i << 1]       = tmp;     lc[i << 1 | 1] = rc[i << 1 | 1]   = tmp;     lazy[i] = -1; }     void dfs1(int x, int fa, int dep){     sz[x] = 1;     deep[x] = dep;       if (fa){                 f[x][0] = fa;         for (int i = 0; f[f[x][i]][i]; ++i) f[x][i + 1] = f[f[x][i]][i];     }       int ct = (int)v[x].size();       rep(i, 0, ct - 1){         int u = v[x][i];         if (u == fa) continue;         dfs1(u, x, dep + 1);         sz[x] += sz[u];         if (sz[son[x]] < sz[u]) son[x] = u;     } }   void dfs2(int x, int tp){     h[x] = ++tot;     top[x] = tp;     if (son[x]) dfs2(son[x], tp);           int ct = (int)v[x].size();     rep(i, 0, ct - 1){         int u = v[x][i];         if (u == f[x][0] || u == son[x]) continue;         dfs2(u, u);     } }   void build(int i, int L, int R){     s[i] = 1;     lazy[i] = -1;       if (L == R) return;     int mid = (L + R) >> 1;       build(lson);     build(rson); }   void change(int i, int L, int R, int l, int r, int val){     pushdown(i, L, R);     if (L == l && R == r){         lc[i] = rc[i] = val;         s[i]  = 1;         lazy[i] = val;         return;     }       int mid = (L + R) >> 1;     if (r <= mid) change(lson, l, r, val);     else if (l > mid) change(rson, l, r, val);     else{         change(lson, l, mid, val);         change(rson, mid + 1, r, val);     }       pushup(i); }   int query(int i, int L, int R, int l, int r){     pushdown(i, L, R);     if (L == l && R == r) return s[i];       int mid = (L + R) >> 1;     if (r <= mid) return query(lson, l, r);     else if (l > mid) return query(rson, l, r);     else{         int tmp = 1;         if (rc[i << 1] ^ lc[i << 1 | 1]) tmp = 0;         return query(lson, l, mid) + query(rson, mid + 1, r) - tmp;     } }   int getcolor(int i, int L, int R, int x){     pushdown(i, L, R);     if (L == R) return lc[i];     int mid = (L + R) >> 1;     if (x <= mid) return getcolor(lson, x);     else return getcolor(rson, x); }   int solvesum(int x, int tp){     int ret = 0;     for (; top[x] ^ top[tp] ;){         ret += query(1, 1, n, h[top[x]], h[x]);         if (getcolor(1, 1, n, h[top[x]]) == getcolor(1, 1, n, h[f[top[x]][0]])) --ret;         x = f[top[x]][0];     }       ret += query(1, 1, n, h[tp], h[x]);     return ret; }   void solvechange(int x, int tp, int val){     for (; top[x] ^ top[tp]; ){         change(1, 1, n, h[top[x]], h[x], val);         x = f[top[x]][0];     }       change(1, 1, n, h[tp], h[x], val); }     void solve(){     int x, y, z;     dfs1(1, 0, 0);     dfs2(1, 1);     build(1, 1, n);     rep(i, 1, n) change(1, 1, n, h[i], h[i], c[i]);       rep(i, 1, m){         char ch[10];         scanf("%s", ch);         if (ch[0] == 'Q'){             scanf("%d%d", &x, &y);             int t = LCA(x, y);             printf("%d\n", solvesum(x, t) + solvesum(y, t) - 1);         }         else{             scanf("%d%d%d", &x, &y, &z);             int t = LCA(x, y);             solvechange(x, t, z);             solvechange(y, t, z);         }     } }   void init(){     scanf("%d%d", &n, &m);     rep(i, 1, n) scanf("%d", c + i);     rep(i, 2, n){         int x, y;         scanf("%d%d", &x, &y);         v[x].push_back(y);         v[y].push_back(x);     } }     int main(){     init();     solve();     return 0; }