一维树状数组BIT

#include<iostream>
#include<cstdio>
using namespace std;
const int maxn = 107;
int D[maxn];
int Bit[maxn];
int n;
//Bit[i]中存储的是i和前头共(i&-i)个数字

//实现求sum和D[i]+=x的操作
int sum(int i)
{
int ret = 0;
while (i)
{
ret += Bit[i];
i -= (i&-i);
}
return ret;
}
void add(int i, int x)
{
while (i <= n)
{
Bit[i] += x;
i += (i&-i);
}
}

void show()
{
cout << "show the awrry:" << endl;
for (int i = 1; i <= n; i++)
{
if (i != 1)
cout << " ";
cout << D[i];
}
cout << endl;
}
int main()
{
memset(Bit, 0, sizeof(Bit));
ios::sync_with_stdio(false);
cout << "please input n" << endl;
cin >> n;
cout << "please input " << n << "nums" << endl;
for (int i = 1; i <= n; i++)
{
cin >> D[i];
}
for (int i = 1; i <= n; i++)
{
add(i, D[i]);
}
cout << "please input q" << endl;
int q;
cin >> q;
cout << "please input q id and x" << endl;
for (int i = 0; i<q; i++)
{
int id, x;
cin >> id >> x;
D[id] += x;
add(id, x);
}
show();
cout << "please ask quesions:" << endl;
while (true)
{
int x;
cin >> x;
if (x == -1)
{
break;
}
if (x <= n)
cout << sum(x) << endl;
}
return 0;
}