Insertion Sort

http://codeforces.com/problemset/problem/362/C

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
const int maxn = 5000 + 5;
const int INF = 1<<30;
int a[maxn], sum[maxn][maxn], sum2[maxn][maxn];
int main() {
    int n;
    scanf("%d", &n);
    for(int i = 0;i < n; i++) 
        scanf("%d", &a[i]);
    for(int i = 0;i < n; i++) {
        sum[i][i] = 0;
        for(int j = i+1;j < n; j++) {
            sum[i][j] = sum[i][j-1];
            if(a[j] < a[i])
                sum[i][j]++;
        }
        sum2[i][i] = 0;
        for(int j = i-1;j >= 0; j--) {
            sum2[i][j] = sum2[i][j+1];
            if(a[i] > a[j])
                sum2[i][j]++;
        }
    }
    int tot = 0;
    for(int i = 0;i < n; i++) {
        for(int j = i+1;j < n; j++) if(a[i] > a[j])
            tot++;
    }
    int mn = INF, ans = 0;
    for(int i = 0;i < n; i++) {
        for(int j = i+1;j < n; j++) {
            int cur = tot + (j-i) - 2*sum[i][j-1] + 2*sum2[j][i+1] - (j-i);
            if(a[i] > a[j]) cur--;
            else    cur++;
            if(cur < mn) {
                mn = cur; ans = 1;
            }
            else if(cur == mn)  ans++;
        }
    }
    printf("%d %d
", mn, ans);
    return 0;
}