Here you will find solutions of many problems on spoj. If you want solution of some problem which is not listed in blog or have doubt regarding any spoj problem (which i have solved) or any programming concept (data structure) you can mail me @ raj.nishant360@gmail.com
And my humble request to you all that don't copy the code only try to understand the logic and algorithm behind the code. I have started this because if you tried as hard as you can and still can't find any solution to the problem then you can refer to this.
You can read my answer how to start competitive programming CLICK HERE

Tuesday, October 21, 2014

DCEPC206 - Its a Murder!

Its a Murder!

Given below code is for decpc206 spoj or its a murder spoj .

Hint : - > BIT 



#include <bits/stdc++.h>
using namespace std;
#define LL long long 
#define MAX 100001
LL tree[100009];
LL read(int pos)
{
    LL res = 0;
    while(pos)
    {
        res += tree[pos];
        pos -= (pos & -pos);
    }
    return res;
}
void update(int pos , int val)
{
    while(pos<=MAX)
    {
        tree[pos] += val;
        pos +=(pos & -pos);
    }
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n;
        scanf("%d",&n);
        int arr[n+9] , hold[n+9] ;
        for(int i = 0; i < n ; i++){
            scanf("%d",&arr[i]);
            hold[i] = arr[i];
        }
        sort(arr,arr+n);
        for(int i = 0; i < n ; i++)
        {
            int pos = lower_bound(arr , arr + n , hold[i]) - arr;
            hold[i] = pos;
        }
        LL sum = 0;
        memset(tree, 0 , sizeof tree);
        for(int i = 0; i < n ; i++)
        {
            sum += read(hold[i]);
            update(hold[i] + 1 , arr[hold[i]]);
        }
        printf("%lld\n",sum);
    }
    return 0;
}