LightOJ 1348 Aladdin and the Return Journey 树链剖分

树链剖分简单题

#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>

using namespace std;

const int MAXN = 100010;

struct Edge {
int to ;
Edge * next;
}E[MAXN*2],*EE;

struct Gragh {
Edge * first;
}G[MAXN];

struct Tree {
int x,y;
int value;
int lazy;
}t[MAXN<<2];

int pre[MAXN],son[MAXN],siz[MAXN],dep[MAXN],top[MAXN],pos[MAXN],Rank[MAXN];
int N,Q,S;
int num[MAXN];
int idx[MAXN];
int tree_idx = 0;
int tot ;

void Init() {
EE = E;
dep[1] = 1;
pre[1] = 0;
tree_idx = 0;
memset(G,0,sizeof(G));
memset(son,0,sizeof(son));
}

// void addedge(int u,int v,int value,int id) {
//     EE->to = v ; EE->next = G[u].first ; EE->value = value ; EE->id = id ; G[u].first = EE++;
//     EE->to = u ; EE->next = G[v].first ; EE->value = value ; EE->id = id ; G[v].first = EE++;
// }

void addedge(int u,int v) {
EE->to = v ; EE->next = G[u].first ; G[u].first = EE++;
EE->to = u ; EE->next = G[v].first ; G[v].first = EE++;
}

void dfs1(int u) {
siz[u] = 1;
son[u] = 0;
for(Edge * p = G[u].first ; p ; p = p -> next) {
if(p->to != pre[u]) {
pre[p->to] = u;
dep[p->to] = dep[u] + 1;
dfs1(p->to);
siz[u] += siz[p->to];
if(siz[p->to] > siz[son[u]])
son[u] = p -> to;
}
}
}

void dfs2(int u,int ancestor) {
top[u] = ancestor;
tree_idx ++;
pos[u] = tree_idx;
if(son[u] != 0) {
dfs2(son[u],ancestor);
}
for(Edge * p = G[u].first ; p ; p = p -> next) {
if(p->to != pre[u] && p->to != son[u]) {
dfs2(p->to,p->to);
// num[pos[p->to]] = p->value;
// idx[p->id] = pos[p->to];
}
// else if(p->to == son[u]) {
//     num[pos[p->to]] = p->value;
//     idx[p->id] = pos[p->to];
// }
}
}

void Push_Up(int rt) {
t[rt].value = t[rt<<1].value + t[rt<<1|1].value;
}

void Build(int x,int y,int rt) {
t[rt].x = x ; t[rt].y = y; t[rt].lazy = 0;
if(x == y) {
t[rt].value = Rank[x];
return ;
}
int mid = (x + y) >> 1;
Build(x,mid,rt<<1);
Build(mid+1,y,rt<<1|1);
Push_Up(rt);
}

void Update(int rt,int position,int value) {
if(t[rt].x == t[rt].y) {
t[rt].value = value;
return ;
}
int mid = (t[rt].x + t[rt].y) >> 1;
if(mid >= position) {
Update(rt<<1,position,value);
}
else {
Update(rt<<1|1,position,value);
}
Push_Up(rt);
}

int Query(int rt,int left,int right) {
if(left <= t[rt].x && right >= t[rt].y) {
return t[rt].value;
}
int ans = 0;
int mid = (t[rt].x + t[rt].y) >> 1;
// Push_Down(rt);
if(mid >= left) {
ans += Query(rt<<1,left,right);
}
if(mid < right){
ans += Query(rt<<1|1,left,right);
}
return ans;
}

// void Change(int x,int y,int lazy) {
//     //printf("lazy : %d\n",lazy);
//     while(top[x] != top[y]) {
//         if(dep[top[x]] < dep[top[y]]) swap(x,y);
//         Update(1,pos[top[x]],pos[x],lazy);
//         x = pre[top[x]];
//     }
//     if(dep[x] > dep[y]) swap(x,y);
//     Update(1,pos[x],pos[y],lazy);
// }

int Query_Tree(int x,int y) {
int ans = 0;
while(top[x] != top[y]) {
if(dep[top[x]] < dep[top[y]]) swap(x,y);
ans += Query(1,pos[top[x]],pos[x]);
x = pre[top[x]];
}
//if(x == y) return ans;
if(dep[x] > dep[y]) swap(x,y);
ans += Query(1,pos[x],pos[y]);
return ans;
}

// void print_tree(int rt) {
//     printf("x : %d y : %d lazy : %d\n",t[rt].x,t[rt].y,t[rt].lazy);
//     if(t[rt].x == t[rt].y) {
//         printf("%d ",t[rt].value);
//         return ;
//     }
//     print_tree(rt<<1);
//     print_tree(rt<<1|1);
// }

int ReadInt() {
char c = getchar();
while(c > '9' || c < '0') c = getchar();
int ret = 0;
while(c <= '9' && c >= '0') {
ret = ret * 10 + c - '0';
c = getchar();
}
return ret;
}

void input() {
int u,v,value;
for(int i = 1 ; i <= N ; i++) {
scanf("%d",num+i);
}
for(int i = 1 ; i <= N - 1 ; i++) {
scanf("%d %d",&u,&v);
u ++ ; v ++ ;
addedge(u,v);
}
dfs1(1);
dfs2(1,1);
for(int i = 1 ; i <= N ; i++) {
Rank[pos[i]] = num[i];
}
Build(1,N,1);
int op;
scanf("%d",&Q);
for(int i = 1 ; i <= Q ; i ++) {
scanf("%d",&op) ;
if(op == 1) {
scanf("%d %d",&u,&value);
u ++;
Update(1,pos[u],value);
}
else {
scanf("%d %d",&u,&v);
u ++; v++;
printf("%d\n",Query_Tree(u,v));
}
//print_tree(1);
//puts("");
}
}

int main(void) {
freopen("a.in","r",stdin);
int T;
int casenum = 1;
scanf("%d",&T);
while(T--) {
printf("Case %d:\n",casenum++);
scanf("%d",&N);
Init();
input();
//solve();
}
return 0;
}