恩恩树链剖分一下
于是用线段树维护每一个子段的颜色信息 --不同颜色段数,因为要合并所以还要维护每一段的左右端点颜色信息
然后就没有然后了2333
尝试着写了个指针版的。。。感觉还可以啊
(话说,是不是写多棵线段树会快啊?)
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 /************************************************************** 2 Problem: 2243 3 User: rausen 4 Language: C++ 5 Result: Accepted 6 Time:4176 ms 7 Memory:31324 kb 8 ****************************************************************/ 9 10 #include <cstdio> 11 #include <algorithm> 12 13 using namespace std; 14 const int N = 100005; 15 const int M = N << 2; 16 const int Maxlen = N * 75; 17 18 char buf[Maxlen], *C = buf; 19 int Len; 20 21 struct edge { 22 int next, to; 23 edge() {} 24 edge(int _n, int _t) : next(_n), to(_t) {} 25 } e[N << 1]; 26 27 int first[N], tot; 28 29 struct tree_node { 30 int sz, dep, fa, son, top, w; 31 } tr[N]; 32 33 int cnt_tree; 34 35 struct seg_node { 36 seg_node *lson, *rson; 37 int l, r, sz, tag, lc, rc; 38 39 inline void fill(int _s, int _t) { 40 sz = _s; 41 tag = _t, lc = _t, rc = _t; 42 } 43 } *root, mempool[M], *cnt_seg = mempool; 44 45 int n, Q, c[N]; 46 47 inline int read() { 48 int x = 0; 49 while (*C < '0' || '9' < *C) ++C; 50 while ('0' <= *C && *C <= '9') 51 x = x * 10 + *C - '0', ++C; 52 return x; 53 } 54 55 inline void Add_Edges(int x, int y) { 56 e[++tot] = edge(first[x], y), first[x] = tot; 57 e[++tot] = edge(first[y], x), first[y] = tot; 58 } 59 60 61 void dfs(int p) { 62 int x, y; 63 tr[p].sz = 1; 64 for (x = first[p]; x; x = e[x].next) 65 if ((y = e[x].to) != tr[p].fa) { 66 tr[y].dep = tr[p].dep + 1, tr[y].fa = p; 67 dfs(y); 68 tr[p].sz += tr[y].sz; 69 if (!tr[p].son || tr[tr[p].son].sz < tr[y].sz) 70 tr[p].son = y; 71 } 72 } 73 74 void DFS(int p) { 75 tr[p].w = ++cnt_tree; 76 if (!tr[p].son) return; 77 tr[tr[p].son].top = tr[p].top; 78 DFS(tr[p].son); 79 int x, y; 80 for (x = first[p]; x; x = e[x].next) 81 if ((y = e[x].to) != tr[p].fa && y != tr[p].son) { 82 tr[y].top = y; 83 DFS(y); 84 } 85 } 86 87 88 #define L p -> l 89 #define R p -> r 90 #define Lc p -> lc 91 #define Rc p -> rc 92 #define Sz p -> sz 93 #define Tag p -> tag 94 #define Lson p -> lson 95 #define Rson p -> rson 96 #define mid (l + r >> 1) 97 void seg_build(seg_node *&p, int l, int r) { 98 p = ++cnt_seg; 99 L = l, R = r, Sz = 1, Tag = -1; 100 if (l == r) return; 101 seg_build(Lson, l, mid), seg_build(Rson, mid + 1, r); 102 } 103 #undef mid 104 105 inline void seg_push_up(seg_node *p) { 106 Lc = Lson -> lc, Rc = Rson -> rc; 107 Sz = Lson -> sz + Rson -> sz; 108 if (Lson -> rc == Rson -> lc) Sz -= 1; 109 } 110 111 inline void seg_push_down(seg_node *p) { 112 if (Tag == -1 || L == R) { 113 Tag = -1; 114 return; 115 } 116 (*Lson).fill(1, Tag); 117 (*Rson).fill(1, Tag); 118 Tag = -1; 119 } 120 121 #define mid (L + R >> 1) 122 void seg_update(seg_node *p, int l, int r, int c) { 123 seg_push_down(p); 124 if (l == L && R == r) { 125 (*p).fill(1, c); 126 return; 127 } 128 if (r <= mid) seg_update(Lson, l, r, c); 129 else if (mid < l) seg_update(Rson, l, r, c); 130 else { 131 seg_update(Lson, l, mid, c); 132 seg_update(Rson, mid + 1, r, c); 133 } 134 seg_push_up(p); 135 } 136 137 int seg_query_cnt(seg_node *p, int l, int r) { 138 seg_push_down(p); 139 if (l == L && R == r) return Sz; 140 if (r <= mid) return seg_query_cnt(Lson, l, r); 141 else if (mid < l) return seg_query_cnt(Rson, l, r); 142 else { 143 return seg_query_cnt(Lson, l, mid) + seg_query_cnt(Rson, mid + 1, r) - 144 (Lson -> rc == Rson -> lc); 145 } 146 } 147 148 int seg_query_color(seg_node *p, int pos) { 149 seg_push_down(p); 150 if (L == R) return Lc; 151 if (pos <= mid) return seg_query_color(Lson, pos); 152 else return seg_query_color(Rson, pos); 153 } 154 #undef mid 155 156 157 void work_change(int x, int y, int c) { 158 while (tr[x].top != tr[y].top) { 159 if (tr[tr[x].top].dep < tr[tr[y].top].dep) 160 swap(x, y); 161 seg_update(root, tr[tr[x].top].w, tr[x].w, c); 162 x = tr[tr[x].top].fa; 163 } 164 if (tr[x].dep < tr[y].dep) 165 swap(x, y); 166 seg_update(root, tr[y].w, tr[x].w, c); 167 } 168 169 int work_sum(int x, int y) { 170 int res = 0; 171 while (tr[x].top != tr[y].top) { 172 if (tr[tr[x].top].dep < tr[tr[y].top].dep) 173 swap(x, y); 174 res += seg_query_cnt(root, tr[tr[x].top].w, tr[x].w); 175 x = tr[x].top; 176 if (seg_query_color(root, tr[x].w) == seg_query_color(root, tr[tr[x].fa].w)) 177 --res; 178 x = tr[x].fa; 179 } 180 if (tr[x].dep < tr[y].dep) 181 swap(x, y); 182 res += seg_query_cnt(root, tr[y].w, tr[x].w); 183 return res; 184 } 185 186 inline void work() { 187 int x, y, z; 188 while (*C != 'C' && *C != 'Q') ++C; 189 if (*C == 'Q') { 190 x = read(), y = read(); 191 printf("%d ", work_sum(x, y)); 192 } else { 193 x = read(), y = read(), z = read(); 194 work_change(x, y, z); 195 } 196 } 197 198 void build() { 199 int i; 200 for (i = 1; i <= n; ++i) 201 c[i] = read(); 202 for (i = 1; i < n; ++i) 203 Add_Edges(read(), read()); 204 tr[1].fa = -1; 205 dfs(1); 206 DFS(1); 207 seg_build(root, 1, n); 208 for (i = 1; i <= n; ++i) 209 seg_update(root, tr[i].w, tr[i].w, c[i]); 210 } 211 212 int main() { 213 Len = fread(C , 1, Maxlen, stdin); 214 buf[Len] = '