/* A recursive function to get the sum of values in given range of the array.
The following are parameters for this function.
st --> Polong long inter to segment tree
index --> Index of current node in the segment tree. Initially 0 is
passed as root is always at index 0
ss & se --> Starting and ending indexes of the segment represented by
current node, i.e., st[index]
qs & qe --> Starting and ending indexes of query range */
unsigned long long int getSumUtil(long long int *st, long long int ss, long long int se, long long int qs, long long int qe, long long int index)
{
// If segment of this node is a part of given range, then return the
// sum of the segment
if (qs <= ss && qe >= se)
return st[index];
// If segment of this node is outside the given range
if (se < qs || ss > qe)
return 0;
// If a part of this segment overlaps with the given range
unsigned long long int mid = getMid(ss, se);
return getSumUtil(st, ss, mid, qs, qe, 2*index+1) +
getSumUtil(st, mid+1, se, qs, qe, 2*index+2);
}
/* A recursive function to get the sum of values in given range of the array.
The following are parameters for this function.
st --> Pointer to segment tree
si --> Index of current node in the segment tree. Initially 0 is
passed as root is always at index 0
ss & se --> Starting and ending indexes of the segment represented by
current node, i.e., st[si]
qs & qe --> Starting and ending indexes of query range */
int getSumUtil(int *st, int ss, int se, int qs, int qe, int si)
{
// If segment of this node is a part of given range, then return the
// sum of the segment
if (qs <= ss && qe >= se)
return st[si];
// If segment of this node is outside the given range
if (se < qs || ss > qe)
return 0;
// If a part of this segment overlaps with the given range
int mid = getMid(ss, se);
return getSumUtil(st, ss, mid, qs, qe, 2*si+1) +
getSumUtil(st, mid+1, se, qs, qe, 2*si+2);
}
// Return sum of elements in range from index qs (quey start) to
// qe (query end). It mainly uses getSumUtil()
lint getSum(lint *st, lint n, lint qs, lint qe)
{
// Check for erroneous input values
if (qs < 0 || qe > n-1 || qs > qe)
{
return 0;
}
return getSumUtil(st, 0, n-1, qs, qe, 0);
}
// Return sum of elements in range from index qs (quey start) to
// qe (query end). It mainly uses getSumUtil()
int getSum(int *st, int n, int qs, int qe)
{
// Check for erroneous input values
if (qs < 0 || qe > n-1 || qs > qe)
{
printf("Invalid Input");
return -1;
}
return getSumUtil(st, 0, n-1, qs, qe, 0);
}
// Return sum of elements in range from index qs (quey start) to
// qe (query end). It mainly uses getSumUtil()
unsigned long long int getSum(long long int *st, long long int n, long long int qs, long long int qe)
{
// Check for erroneous input values
return getSumUtil(st, 0, n-1, qs, qe, 0);
}
