data_structures::SegmentTree< T > Class Template Reference

class representation of the segment tree More...

Public Member Functions
	SegmentTree (int n)
void	update (int pos, T val)
	Updates a value at a certain position.
T	range_comb (int l, int r)
	Returns comb across all values between l and r.

Private Member Functions
T	comb (T x, T y)
	Any associative function that combines x and y.
int	mid (int l, int r)
	Gives the midpoint between two integers.
void	update (int i, int l, int r, int pos, T val)
	Helper method for update method below.
T	range_comb (int i, int l, int r, int tl, int tr)
	Helper method for range_comb method below.

Private Attributes
const T	ID = 0
	Comb(ID, x) = x.
std::vector< T >	t
	Vector to represent the tree.
int	size = 0
	Number of elements available for querying in the tree.

Detailed Description

template<class T>
class data_structures::SegmentTree< T >

class representation of the segment tree

Template Parameters

T	The type of the class that goes in the datastructure

Constructor & Destructor Documentation

SegmentTree()

template<class T >

data_structures::SegmentTree< T >::SegmentTree ( int  n )

inline

: t(n * 4, ID), size(n) {}

Member Function Documentation

comb()

template<class T >

T data_structures::SegmentTree< T >::comb ( T  x, T  y  )

inlineprivate

Any associative function that combines x and y.

Parameters

x	The first operand
y	The second operand

Returns

Some associative operation applied to these two values. In this case, I used addition

                     {
        return x + y;
    }

mid()

template<class T >

int data_structures::SegmentTree< T >::mid ( int  l, int  r  )

inlineprivate

Gives the midpoint between two integers.

Parameters

l	The left endpoint
r	The right endpoint

Returns

the middle point between them

                          {
        return l + (r - l) / 2;
    }

range_comb() [1/2]

template<class T >

T data_structures::SegmentTree< T >::range_comb ( int  i, int  l, int  r, int  tl, int  tr  )

inlineprivate

Helper method for range_comb method below.

Parameters

i	The current node
l	The leftmost node of the current node
r	The rightmost node of the current node
tl	The left endpoint of the range
tr	The right endpoint of the range

Returns

The comb operation applied to all values between tl and tr

                                                      {
        if(l == tl && r == tr) return t[i];
        if(tl > tr) return 0;
        int m = mid(l, r);
        return comb(range_comb(i * 2, l, m, tl, std::min(tr, m)), range_comb(i * 2 + 1, m + 1, r, std::max(tl, m + 1), tr));
    }

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range_comb() [2/2]

template<class T >

T data_structures::SegmentTree< T >::range_comb ( int  l, int  r  )

inline

Returns comb across all values between l and r.

Parameters

l	The left endpoint of the range
r	The right endpoint of the range

Returns

The value of the comb operations

                               {
        return range_comb(1, 1, size, l, r);
    }

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update() [1/2]

template<class T >

void data_structures::SegmentTree< T >::update ( int  i, int  l, int  r, int  pos, T  val  )

inlineprivate

Helper method for update method below.

Parameters

i	The index of the current node
l	The leftmost node of the current node
r	The rightmost node of the current node
pos	The position to update
val	The value to update it to

                                                     {
        if(l == r) t[i] = val;
        else {
            int m = mid(l, r);
            if(pos <= m) update(i * 2, l, m, pos, val);
            else update(i * 2 + 1, m + 1, r, pos, val);
            t[i] = comb(t[i * 2], t[i * 2 + 1]);
        }
    }

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update() [2/2]

template<class T >

void data_structures::SegmentTree< T >::update ( int  pos, T  val  )

inline

Updates a value at a certain position.

Parameters

pos	The position to update
val	The value to update it to

                                {
        update(1, 1, size, pos, val);
    }

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The documentation for this class was generated from the following file:

• data_structures/segment_tree.cpp