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("\n");for(int i=0;i<(N);i++) 19 {for(int j=0;j<(M);j++){ 20 printf("%d",G[i][j]);}printf("\n");}
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\n",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\n",x,segtree[x].l,segtree[x].r,segtree[x].num);
101 //printf("lcost:%d rcost:%d\n",segtree[x].lcost,segtree[x].rcost);
102 //printf("l->rcost:%d r->lcost:%d\n",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\n",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\n",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\n",(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*\n",query(1,id[son[v]],id[u]));
234
235 //printf("last_u:%d last_v:%d\n",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\n",(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\n",(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\n",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\n",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\n",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("-----------------\n");
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\n",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 }
时间： 2024-10-24 11:58:31