标签：des blog http io ar os sp for strong
Description
During Frosh Week, students play various fun games to get to know each other and compete against other teams. In one such game, all the frosh on a team stand in a line, and are then asked to arrange themselves according to some criterion, such as their height, their birth date, or their student number. This rearrangement of the line must be accomplished only by successively swapping pairs of consecutive students. The team that finishes fastest wins. Thus, in order to win, you would like to minimize the number of swaps required.
3 3 1 2
2
#include <stdio.h>
#define N 1000001
typedef long long LL;
int n;
int num[N], tmp[N];
int input()
{
if (scanf("%d", &n) != 1) return 0;
int i;
for (i = 0; i < n; i++) {
scanf("%d", &num[i]);
}
return 1;
}
LL mergesort(int l, int r, int a[])
{
if (l >= r) return 0;
int m = (l + r) >> 1;
LL s1 = mergesort(l, m, a);
LL s2 = mergesort(m + 1, r, a);
LL sum = s1 + s2;
int p = l, q = m + 1;
int k = l;
while (p <= m || q <= r) {
if (p > m || (q <= r && a[p] > a[q])) {
tmp[k++] = a[q++];
sum += m + 1 - p;
} else {
tmp[k++] = a[p++];
}
}
int i;
for (i = l; i <= r; i++) {
a[i] = tmp[i];
}
return sum;
}
void solve()
{
LL ans = mergesort(0, n - 1, num);
printf("%lld\n", ans);
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("d:\\OJ\\uva_in.txt", "r", stdin);
#endif
while (input()) {
solve();
}
return 0;
}
标签：des blog http io ar os sp for strong
原文地址：http://www.cnblogs.com/a972290869/p/4108313.html
