洛谷P3384【模板】树链剖分 (树链剖分)

题目

题解

代码

#include <iostream>
#include <cstdio>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define N 100005

using namespace std;

int n, m, Root, MOD, cur, head_p
, Tim;
int num
, fa
, top
, dep
, son
, size
, start
, end
, fw
;

struct Tadj{int next, obj;} Edg[N << 1];
struct Tnode{int sum, add;} tree[N << 2];

void Init(){
cur = -1;
Tim = 0;
memset(head_p, -1, sizeof(head_p));
memset(son, -1, sizeof(son));
}

void Insert(int a, int b){
cur ++;
Edg[cur].next = head_p[a];
Edg[cur].obj = b;
head_p[a] = cur;
}

void dfs1(int root, int dad){
dep[root] = dep[dad] + 1;
fa[root] = dad;
size[root] = 1;
for(int i = head_p[root]; ~ i; i = Edg[i].next){
int v = Edg[i].obj;
if(v == dad)  continue;
dfs1(v, root);
size[root] += size[v];
if(son[root] == -1 || size[v] > size[son[root]])  son[root] = v;
}
}

void dfs2(int root, int tp){
Tim ++;
start[root] = Tim;
fw[Tim] = root;
top[root] = tp;

if(~ son[root])  dfs2(son[root], tp);

for(int i = head_p[root]; ~ i; i = Edg[i].next){
int v = Edg[i].obj;
if(v == fa[root] || v == son[root])  continue;
dfs2(v, v);
}
end[root] = Tim;
}

void build(int root, int L, int R){
if(L == R){
tree[root].sum = num[fw[L]] % MOD;
return;
}

int mid = (L + R) >> 1, Lson = root << 1, Rson = root << 1 | 1;
build(Lson, L, mid);
build(Rson, mid+1, R);

tree[root].sum = (tree[Lson].sum + tree[Rson].sum) % MOD;
}

void down(int root, int L, int R){
if(tree[root].add == 0)  return;
int mid = (L + R) >> 1, Lson = root << 1, Rson = root << 1 | 1;
tree[Lson].add = (tree[Lson].add + tree[root].add) % MOD;
tree[Rson].add = (tree[Rson].add + tree[root].add) % MOD;

tree[Lson].sum = (tree[Lson].sum + (tree[root].add*(mid-L+1)%MOD)%MOD) % MOD;
tree[Rson].sum = (tree[Rson].sum + (tree[root].add*(R-mid)%MOD)%MOD) % MOD;
tree[root].add = 0;
}

void update(int root, int L, int R, int x, int y, int val){
if(x > R || y < L)  return;
if(x <= L && y >= R){
tree[root].sum = (tree[root].sum + ((R - L + 1)%MOD * val)%MOD) % MOD;
tree[root].add = (tree[root].add + val) % MOD;
return;
}

int mid = (L + R) >> 1, Lson = root << 1, Rson = root << 1 | 1;
down(root, L, R);
update(Lson, L, mid, x, y, val);
update(Rson, mid+1, R, x, y, val);

tree[root].sum = (tree[Lson].sum + tree[Rson].sum) % MOD;
}

int query(int root, int L, int R, int x, int y){
if(x > R || y < L)  return 0;
if(x <= L && y >= R)  return tree[root].sum;

int mid = (L + R) >> 1, Lson = root << 1, Rson = root << 1 | 1;
down(root, L, R);
int tmp1 = query(Lson, L, mid, x, y);
int tmp2 = query(Rson, mid+1, R, x, y);

return (tmp1 + tmp2) % MOD;
}

void work1(int x, int y, int val){
while(top[x] != top[y]){
if(dep[top[x]] > dep[top[y]])  swap(x, y);
update(1, 1, n, start[top[y]], start[y], val);
y = fa[top[y]];
}
if(dep[x] > dep[y])  swap(x, y);
update(1, 1, n, start[x], start[y], val);
}

int work2(int x, int y){

int ans = 0;
while(top[x] != top[y]){
if(dep[top[x]] > dep[top[y]])  swap(x, y);
ans = (ans + query(1, 1, n, start[top[y]], start[y])) % MOD;
y = fa[top[y]];
}
if(dep[x] > dep[y])  swap(x, y);
ans = (ans + query(1, 1, n, start[x], start[y])) % MOD;
return ans;
}

int main(){

scanf("%d%d%d%d", &n, &m, &Root, &MOD);

Init();

for(int i = 1; i <= n; i++)
scanf("%d", &num[i]);

int a, b;
for(int i = 1; i < n; i++){
scanf("%d%d", &a, &b);
Insert(a, b);
Insert(b, a);
}

dfs1(Root, 0);
dfs2(Root, Root);

build(1, 1, n);

int op, k;
for(int i = 1; i <= m; i++){
scanf("%d", &op);
if(op == 1){
scanf("%d%d%d", &a, &b, &k);
work1(a, b, k % MOD);
}
else if(op == 2){
scanf("%d%d", &a, &b);
printf("%d\n", work2(a, b));
}
else if(op == 3){
scanf("%d%d", &a, &b);
update(1, 1, n, start[a], end[a], b % MOD);
}
else{
scanf("%d", &a);
printf("%d\n", query(1, 1, n, start[a], end[a]));
}
}

return 0;
}