Here is my simplest C++ implementation for heap. The code is well-commented.
/*
Usage:
heap Heap;
Heap.clear();
Heap.insert(value);
Heap.remove();
Heap.print();
*/
struct heap {
int myarray[NN+1]; // myarray to store the numbers as heap, 1 indexed
int n; // the number of nodes in my array
heap() { // constructor
clear(); // we clear the heap
}
void clear() { // initialize the heap
n = 0; // initially there are no nodes in the heap
}
void insert( int K ) { // inserting an element K in the heap
if( n == NN ) { // the heap is full
printf("cannot insert any more element, the heap is full\n");
return;
}
++n; // so, we have a new element, we increased n before adding
// the element because we start from index 1
myarray[n] = K; // inserted the element at the rightmost position
int p = n; // for keeping the current position
while( p > 1 ) { // p = 1 means we are on the root, and its a heap
int pr = p / 2; // pr is the parent of p
if( myarray[pr] > myarray[p] ) { // parent is greater than child
swap( myarray[pr], myarray[p] );
p = pr; // now the new position of the current element is pr
} else break; // otherwise its a heap, so we can stop here
}
}
int remove() { // removing the minimum element from the heap
if( n == 0 ) { // is the heap is empty
printf("The heap is empty, cannot delete.\n");
return -1;
}
int K = myarray[1]; // first element in the heap is the minimum
myarray[1] = myarray[n]; // brought the last element in 1st position
n--; // as we removed one element, now we need to maintain the heap
int p = 1; // as we moved the rightmost element in index 1
while( 2 * p <= n ) { // means p has at least one child, if 2*p > n
// we are sure that p is in the last level
int ch = 2 * p; // contains the index of the child
if( 2 * p + 1 <= n ) { // right child exists
if( myarray[ch] > myarray[ch+1] ) // right child is smaller
// than left child
ch++; // ch contains the index of the right child
}
if( myarray[p] > myarray[ch] ) { // so, current node is larger
// than its child
swap( myarray[p], myarray[ch] );
p = ch; // new position of the current element
} else break; //current node is smaller than its children, so heap
}
return K; // as we stored the minimum element in K
}
void print() { // printing the heap
printf("Number of elements: %d\n", n);
for( int i = 1; i <= n; i++ ) printf("%d ", myarray[i]);
printf("\n");
}
// Time: O(nlogn)
// Extra space: O(1) as we will pass the input array as res here
void heapSort(int* res) {
for(int i = 0, len = n; i < len; ++i) {
res[i] = remove();
}
}
};
2
solved how do i implement heap data structure using c++? [closed]