洛谷P3384【模板】树链剖分 (树链剖分)

题目

题目传送门

题解

树链剖分模板题，积累一下模板

代码

#include 
#include 
#include 
#include 
#include 
#define N 100005

using namespace std;

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

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;
}

Smile.