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AcWing 1264 线段树解法

穿裙子的程序员 2022-03-25 阅读 51

线段树的单点修改和区间查询

#include<bits/stdc++.h>

using namespace std;

const int N = 1e5 + 10;

int n, m;
int w[N];
struct node{
	int l, r;
	
	int sum;
}tr[N * 4];

void push_up(int u){
	tr[u].sum = tr[u << 1].sum + tr[u << 1 | 1].sum;
}

void build(int u, int l, int r){
	if(l == r) tr[u] = {l, r, w[r]};
	else{
		tr[u] = {l, r};
		int mid = l + r >> 1;
		build(u << 1, l, mid);
		build(u << 1| 1, mid + 1, r);
		push_up(u);
	}
}

int query(int u, int l, int r){
	if(tr[u].l >= l && tr[u].r <= r) return tr[u].sum;	
	int res = 0;
	int mid = tr[u].l + tr[u].r >> 1;
	if(l <= mid) res += query(u << 1, l, r);
	if(r > mid) res += query(u << 1 | 1, l, r);
	return res; 	
}

int modify(int u, int x, int v){
	if(tr[u].l == tr[u].r) tr[u].sum += v;
	else{
		int mid = tr[u].l + tr[u].r >> 1;
		if(x <= mid) modify(u << 1, x, v);
		else modify(u << 1 | 1, x, v);
		push_up(u);
	}
}

int main()
{
	cin>>n>>m;
	
	for(int i = 1; i <= n; i ++ ){
		cin>>w[i];
	}
	
	build(1, 1, n);
	
	while(m -- ){
		int k, a, b;
		cin>>k>>a>>b;
		if(!k) cout<<query(1, a, b)<<endl;
		else modify(1, a, b);
	}
	return 0;
}
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