You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
48 lines
883 B
C++
48 lines
883 B
C++
#include <iostream>
|
|
using namespace std;
|
|
|
|
const int maxn = 200000;
|
|
int t[maxn];
|
|
|
|
void add(int t[], int i, int value) {
|
|
for (; i < maxn; i |= i + 1)
|
|
t[i] += value;
|
|
}
|
|
|
|
// sum[0,i]
|
|
int sum(int t[], int i) {
|
|
int res = 0;
|
|
for (; i >= 0; i = (i & (i + 1)) - 1)
|
|
res += t[i];
|
|
return res;
|
|
}
|
|
|
|
// Returns min(p|sum[0,p]>=sum)
|
|
int lower_bound(int t[], int sum) {
|
|
--sum;
|
|
int pos = -1;
|
|
for (int blockSize = 1 << 30; blockSize != 0; blockSize >>= 1) {
|
|
if (blockSize > maxn) continue;
|
|
int nextPos = pos + blockSize;
|
|
if (nextPos < maxn && sum >= t[nextPos]) {
|
|
sum -= t[nextPos];
|
|
pos = nextPos;
|
|
}
|
|
}
|
|
return pos + 1;
|
|
}
|
|
|
|
|
|
// Usage example
|
|
int main() {
|
|
add(t, 0, 4);
|
|
add(t, 1, 5);
|
|
add(t, 2, 5);
|
|
add(t, 2, 5);
|
|
|
|
cout << (4 == sum(t, 0)) << endl;
|
|
cout << (19 == sum(t, 2)) << endl;
|
|
cout << (2 == lower_bound(t, 19)) << endl;
|
|
cout << (maxn == lower_bound(t, 20)) << endl;
|
|
}
|