41 lines
1000 B
Markdown
41 lines
1000 B
Markdown
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## [$P3374$ 【模板】树状数组 1](https://www.luogu.com.cn/problem/P3374)
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```cpp {.line-numbers}
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#include <bits/stdc++.h>
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using namespace std;
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typedef long long LL;
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const int N = 5 * 1e5 + 10;
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int n, m;
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int a[N];
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// 树状数组模板
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// 用while循环优于for循环，因为没有i变量，不易写错，代码更短
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#define lowbit(x) (x & -x)
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int c[N];
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void add(int x, int v) {
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while (x < N) c[x] += v, x += lowbit(x);
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}
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LL sum(int x) {
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LL res = 0;
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while (x) res += c[x], x -= lowbit(x);
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return res;
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}
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int main() {
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cin >> n >> m;
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for (int i = 1; i <= n; i++)
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cin >> a[i], add(i, a[i]); // 维护进入树状数组，两个概念：位置，值
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while (m--) {
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int op, x, y;
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cin >> op >> x >> y;
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if (op == 1)
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add(x, y); // 在x位置上加上y
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else
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// 计算[x,y]之间的数字和
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cout << sum(y) - sum(x - 1) << endl;
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}
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return 0;
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}
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```
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