// f is a frequency array. In your case, since n <= 10^5, declare it as int f[100004];

// The 2 methods below are code for Fenwick Tree, super short
int rsq(int b) { // range sum query
    int s = 0;
    while (b) s += f[b], b -= b & -b;
    return s;
}

void adj(int k, int v) { // adjust
     // L should be the maximum value in the array, but the maximum value and the length of the input happens to be the same, so I'm being sloppy here.
     while (k <= L) f[k] += v, k += k & -k;
}

// main
          s = 0; // Number of inversions
          for (i = 1; i <= L; i++) { // L is the number of elements in the array
              ... // Assign the current element in the array to v
              adj(v, 1); // Adjust + 1 at value v in the Fenwick Tree
              s += i - rsq(v); // rsq(v) will be the number of numbers smaller than or equal to v.
                               // i - rsq(v) will be number of numbers strictly larger than v
          }