肯定先无脑树链剖分，然后线段树维护一段区间不同个数，再维护一个左右端点的费用。
线段树更新，pushDown，pushUp的时候要注意考虑链接位置的费用是否相同
还有就是树链剖分操作的时候，维护上一个更新的位置的费用。
总之就是出现区间合并，就考虑总数是否要减一
好想不好写
//场上根本写不完啊
1 /*--------------------------------------------------------------------------------------*/ 2 3 #include <algorithm> 4 #include <iostream> 5 #include <cstring> 6 #include <ctype.h> 7 #include <cstdlib> 8 #include <cstdio> 9 #include <vector> 10 #include <string> 11 #include <queue> 12 #include <stack> 13 #include <cmath> 14 #include <set> 15 #include <map> 16 17 //debug function for a N*M array 18 #define debug_map(N,M,G) printf(" ");for(int i=0;i<(N);i++) 19 {for(int j=0;j<(M);j++){ 20 printf("%d",G[i][j]);}printf(" ");} 21 //debug function for int,float,double,etc. 22 #define debug_var(X) cout<<#X"="<<X<<endl; 23 #define LL long long 24 const int INF = 0x3f3f3f3f; 25 const LL LLINF = 0x3f3f3f3f3f3f3f3f; 26 /*--------------------------------------------------------------------------------------*/ 27 using namespace std; 28 29 int N,M,T; 30 const int maxn = 2e5+100; 31 32 struct Edge{ 33 int x,y,val; 34 }e[maxn]; 35 36 vector <int> G[maxn]; 37 38 int val[maxn],dep[maxn],siz[maxn],top[maxn],id[maxn],son[maxn],fa[maxn]; 39 int topw; 40 41 void init() 42 { 43 for(int i=0;i<maxn;i++) G[i].clear(); 44 topw = 0; 45 } 46 47 void dfs_1(int u,int f,int d) 48 { 49 fa[u] = f; 50 son[u] = 0; 51 siz[u] = 1; 52 dep[u] = d; 53 for(int i=0;i<G[u].size();i++) if(G[u][i] != f) 54 { 55 dfs_1(G[u][i],u,d+1); 56 siz[u] += siz[G[u][i]]; 57 if(siz[son[u]] < siz[G[u][i] ]) 58 { 59 son[u] = G[u][i]; 60 } 61 } 62 } 63 64 void dfs_2(int u,int tp) 65 { 66 top[u] = tp; 67 id[u] = ++topw; 68 if(son[u]) dfs_2(son[u],tp); 69 for(int i=0;i<G[u].size();i++) if(G[u][i]!=fa[u] && G[u][i] != son[u] ) 70 { 71 dfs_2(G[u][i],G[u][i]); 72 } 73 } 74 75 void debug() 76 { 77 for(int i=1;i<=N;i++) 78 { 79 printf("%d siz:%d son:%d dep:%d fa:%d ",i,siz[i],son[i],dep[i],fa[i]); 80 printf("top:%d id:%d ",top[i],id[i]); 81 } 82 return ; 83 } 84 85 /*-----------------------------------*/ 86 #define lson(x) (x<<1) 87 #define rson(x) (x<<1|1) 88 89 struct SegmentTree{ 90 int l,r; 91 int lazy; 92 int num,lcost,rcost; 93 }segtree[4*maxn]; 94 95 void pushUp(int x) 96 { 97 segtree[x].num = segtree[lson(x)].num + segtree[rson(x)].num - (segtree[lson(x)].rcost==segtree[rson(x)].lcost? 1 : 0); 98 segtree[x].lcost = segtree[lson(x)].lcost; 99 segtree[x].rcost = segtree[rson(x)].rcost; 100 //printf("x:%d [%d,%d] num:%d ",x,segtree[x].l,segtree[x].r,segtree[x].num); 101 //printf("lcost:%d rcost:%d ",segtree[x].lcost,segtree[x].rcost); 102 //printf("l->rcost:%d r->lcost:%d ",segtree[lson(x)].rcost,segtree[rson(x)].lcost); 103 } 104 105 void pushDown(int x) 106 { 107 if(segtree[x].lazy != -1) 108 { 109 segtree[lson(x)].lcost = segtree[lson(x)].rcost = segtree[x].lazy; 110 segtree[rson(x)].lcost = segtree[rson(x)].rcost = segtree[x].lazy; 111 segtree[lson(x)].num = segtree[rson(x)].num = 1; 112 segtree[lson(x)].lazy = segtree[rson(x)].lazy = segtree[x].lazy; 113 segtree[x].lazy = -1; 114 } 115 } 116 117 void Build(int l,int r,int x) 118 { 119 segtree[x].l = l; 120 segtree[x].r = r; 121 segtree[x].lazy = -1; 122 if(l == r) 123 { 124 segtree[x].num = 1; 125 segtree[x].lcost = segtree[x].rcost = val[l]; 126 return ; 127 } 128 int mid = (l+r)>>1; 129 Build(l,mid,lson(x)); 130 Build(mid+1,r,rson(x)); 131 pushUp(x); 132 } 133 134 void update(int x,int L,int R,int cost) 135 { 136 if(segtree[x].l >= L && segtree[x].r <= R) 137 { 138 segtree[x].lcost = segtree[x].rcost = cost; 139 segtree[x].num = 1; 140 segtree[x].lazy = cost; 141 return ; 142 } 143 pushDown(x); 144 int mid = (segtree[x].l + segtree[x].r) >> 1; 145 if(L <= mid) update(lson(x),L,R,cost); 146 if(R > mid) update(rson(x),L,R,cost); 147 pushUp(x); 148 return ; 149 } 150 151 int query(int x,int L,int R) 152 { 153 if(segtree[x].l >= L && segtree[x].r <= R) 154 { 155 return segtree[x].num; 156 } 157 pushDown(x); 158 int mid = (segtree[x].l + segtree[x].r) >> 1; 159 int ans = 0; 160 161 if(R <= mid) ans = query(lson(x),L,R); 162 else if(L > mid) ans = query(rson(x),L,R); 163 else ans = query(lson(x),L,R) + query(rson(x),L,R) - (segtree[lson(x)].rcost==segtree[rson(x)].lcost ? 1 : 0) ; 164 pushUp(x); 165 return ans; 166 } 167 168 int query_edge(int x,int pos) 169 { 170 if(segtree[x].l == segtree[x].r) 171 { 172 return segtree[x].lcost; 173 } 174 pushDown(x); 175 int res = 0; 176 int mid = (segtree[x].l + segtree[x].r) >> 1; 177 if(pos <= mid) res = query_edge(lson(x),pos); 178 else res = query_edge(rson(x),pos); 179 pushUp(x); 180 return res ; 181 } 182 183 int Find(int u,int v) 184 { 185 int ans = 0,fu = top[u],fv = top[v]; 186 int last_u=-1 , last_v = -1; 187 int last_u_color,last_v_color; 188 //printf("%d->%d ",u,v); 189 190 while(fu != fv) 191 { 192 if(dep[fu] < dep[fv]) 193 { 194 swap(fu,fv);swap(u,v); 195 swap(last_u,last_v); 196 swap(last_u_color,last_v_color); 197 } 198 199 //printf("query:[%d,%d] %d->%d ",id[fu],id[u],u,fu); 200 //printf("%d ",query(1,id[fu],id[u])); 201 ans += query(1,id[fu],id[u]); 202 if(last_u == -1) 203 { 204 last_u = fu; 205 last_u_color = query_edge(1,id[fu]); 206 } 207 else 208 { 209 if(last_u != -1 && fa[last_u] == u) 210 { 211 //printf("u sub:%d ",(last_u_color==query_edge(1,id[u]) ? 1 : 0)); 212 ans -= (last_u_color==query_edge(1,id[u]) ? 1 : 0); 213 last_u = fu; 214 last_u_color = query_edge(1,id[fu]); 215 } 216 } 217 u = fa[fu]; 218 fu = top[u]; 219 } 220 if(u == v) 221 { 222 if(last_u != -1 && last_v != -1 && last_u_color==last_v_color) ans -= 1; 223 return ans; 224 } 225 if(dep[u] < dep[v]) 226 { 227 swap(u,v); 228 swap(last_u,last_v); 229 swap(last_u_color,last_v_color); 230 } 231 //printf("query:[%d,%d] %d->%d ",id[son[v]],id[u],u,son[v]); 232 ans += query(1,id[son[v] ],id[u]); 233 //printf("%d* ",query(1,id[son[v]],id[u])); 234 235 //printf("last_u:%d last_v:%d ",last_u,last_v); 236 if(last_u != -1 && fa[last_u] == u) 237 { 238 //printf("u sub:%d last_u_color:%d u_color:%d ",(last_u_color==query_edge(1,id[u]) ? 1 : 0),last_u_color,query_edge(1,id[u])); 239 ans -= (last_u_color==query_edge(1,id[u]) ? 1 : 0); 240 last_u = fu; 241 last_u_color = query_edge(1,id[u]); 242 } 243 244 if(last_v != -1 && fa[last_v] == v) 245 { 246 //printf("v sub:%d last_v_color:%d son[v]_color:%d ",(last_v_color==query_edge(1,id[son[v]]) ? 1 : 0),last_v_color,query_edge(1,id[son[v]] )); 247 ans -= (last_v_color==query_edge(1,id[son[v]]) ? 1 : 0); 248 last_v = fv; 249 last_v_color = query_edge(1,id[son[v]]); 250 } 251 252 return ans; 253 } 254 255 void Change(int u,int v,int cost) 256 { 257 int fu = top[u],fv = top[v]; 258 //printf("%d->%d ",u,v); 259 while(fu != fv) 260 { 261 if(dep[fu] < dep[fv]) 262 { 263 swap(fu,fv);swap(u,v); 264 } 265 //printf("change:[%d,%d] %d->%d %d ",id[fu],id[u],u,fu,cost); 266 update(1,id[fu],id[u],cost); 267 u = fa[fu]; 268 fu = top[u]; 269 } 270 if(u == v) return ; 271 if(dep[u] < dep[v]) swap(u,v); 272 //printf("change:[%d,%d] %d->%d %d ",id[son[v]],id[u],u,son[u],cost); 273 update(1,id[son[v]],id[u],cost); 274 return ; 275 } 276 277 int main() 278 { 279 //freopen("input","r",stdin); 280 while(~scanf("%d%d",&N,&M)) 281 { 282 init(); 283 int u,v,w; 284 for(int i=1;i<N;i++) 285 { 286 scanf("%d%d%d",&u,&v,&w); 287 e[i].x = u;e[i].y = v;e[i].val = w; 288 G[u].push_back(v); 289 G[v].push_back(u); 290 } 291 topw = 0; 292 dfs_1(1,0,1); 293 dfs_2(1,1); 294 //debug(); 295 for(int i=1;i<N;i++) 296 { 297 if(dep[e[i].x] < dep[e[i].y]) swap(e[i].x,e[i].y); 298 val[id[e[i].x]] = e[i].val; 299 } 300 301 Build(1,topw,1); 302 char op[20]; 303 //printf("----------------- "); 304 for(int i=0;i<M;i++) 305 { 306 scanf("%s",op); 307 if(op[0] == 'Q') 308 { 309 scanf("%d%d",&u,&v); 310 printf("%d ",Find(u,v)); 311 } 312 else 313 { 314 scanf("%d%d%d",&u,&v,&w); 315 Change(u,v,w); 316 } 317 //puts(""); 318 } 319 } 320 }