1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int a[500005], real[500005], n;
long long tree[500005];
int cmp(const void* a, const void* b)
{
return *(const int*)a - *(const int*)b;
}
void update(int i)
{
while (i)
{
++tree[i];
i -= i & -i;
}
}
long long query(int i)
{
long long ans = 0LL;
while (i <= n)
{
ans += tree[i];
i += i & -i;
}
return ans;
}
int bfind(int val)
{
int l = 0, r = n - 1, m = (l + r) >> 1;
while (l <= r)
{
if (real[m] < val)
l = m + 1;
else if (real[m] > val)
r = m - 1;
else
return m + 1;
m = (l + r) >> 1;
}
return 0;
}
int main()
{
int i;
while (scanf("%d", &n), n)
{
long long ans = 0LL;
memset(tree, 0, sizeof(tree));
for (i = 0; i < n; ++i)
{
scanf("%d", a + i);
real[i] = a[i];
}
qsort(real, n, sizeof(int), cmp);
for (i = 0; i < n; ++i)
{
a[i] = bfind(a[i]);
ans += query(a[i]);
update(a[i] - 1);
}
printf("%I64d\n", ans);
}
return 0;
}
|
