超级树状数组,就是用树状数组来进行区间修改+区间查询操作的东西,好处是和线段树相比快了不少。
例题
首先先来复习一下普通的树状数组
int tree[MAXN];
int lowbit(int x) {return x & -x;
}
void update(int x, int d) {while (x <= n) {tree[x] += d;x += lowbit(x);}
}
int sum(int x) {int ans = 0;while (x) {ans += tree[x];x -= lowbit(x);}return ans;
}
注意: update
是 \(x\sim n\) 都加上 \(d\),sum
是求 \(1\sim x\)。
求区间 \(l\sim r\) 的问题,我们可以转化为求 \(1\sim k\) 的问题,对于这个问题,我们可以定义一个差分数组 \(d_i=a_i - a_{i - 1}\) 显然 \(a_i=d_1 + d_2 + ... + d_i\)。
\[\begin{aligned}&a_1+a_2+...+a_i\\=&~~d_1+(d_1+d_2)+(d_1+d_2+d_3)+...+(d_1+d_2+...+d_i)\\=&~~id_1+(i-1)d_2+...+[i-(i-1)]d_i\\=&~~i\sum\limits_{j=1}^i d_j-\sum\limits_{j=1}^i (j-1)d_j\end{aligned}
\]
当求第一个数时,我们只需将 \(x\) 和 \(y+1\) 这两个差分数组更改,其他的差分数组要么没有被修改,要么被抵消掉了,当求第二个数时,我们也是将那两个数更改,其他的和前面的同理,对于这个数,自己推去吧。
#include <cstring>
#include <cstdio>
#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#define endl '\n'
#define x first
#define y second
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef double db;
typedef pair<ll, ll> pll;inline ll read() {char ch = getchar(); ll fu = 0, s = 0;while(!isdigit(ch)) fu |= (ch == '-'), ch = getchar();while(isdigit(ch)) s = (s << 1) + (s << 3) + (ch ^ 48), ch = getchar();return fu ? -s : s;
}const int MAXN = 1e5 + 10;
int n, m, a[MAXN];
struct Node {ll tree[MAXN];int lowbit(int x) {return x & -x;}void update(int x, ll d) {while (x <= n) {tree[x] += d;x += lowbit(x);}}ll sum(int x) {ll ans = 0;while (x) {ans += tree[x];x -= lowbit(x);}return ans;}
} tr1, tr2;void solve() {n = read(), m = read();for (int i = 1; i <= n; i++) {a[i] = read();ll t = a[i] - a[i - 1];tr1.update(i, t);tr2.update(i, (i - 1) * t);}while (m--) {int op = read(), x = read(), y = read(), k;if (op == 1) {k = read();tr1.update(x, k);tr1.update(y + 1, -k);tr2.update(x, (x - 1) * k);tr2.update(y + 1, -y * k);} else {printf("%lld\n", (tr1.sum(y) * y - tr2.sum(y)) - (tr1.sum(x - 1) * (x - 1) - tr2.sum(x - 1)));}}
}signed main() {int T = 1;// T = read();while(T--) solve();return 0;
}