Chapter 6 "maximum priority queue" in heap sorting"

Use the largest heap to implement the maximum priority queue:

// Returns the maximum value of the heap.
Int heapmaximum (int *)
// Remove and return the element with the maximum keyword in the heap
Int heapextractmax (int * a, int * heapsize)
// Add the key value of element x to K. Here, K cannot be smaller than the original key value of X.
Void heapincreasekey (int * a, int I, int K)
// Insert element x into the heap
Void maxheapinsert (int * a, int * heapsize, int key)

# Include <stdio. h> # include <string. h> # include <time. h> # define buffer_size 10 // heap adjustment to maintain the heap nature void maxheapify (int * a, int I, int heapsize) {int left = I; int right = I; int TMP; int largest = I; while (I <= heapsize) {left = I <1; // left sub-index right = (I <1) + 1; // (the shift operation has a lower priority than the arithmetic operation !) Right sub-index largest = I; If (left <= heapsize & A [I] <A [left]) {largest = left ;} if (right <= heapsize & A [Largest] <A [right]) {largest = right;} if (I! = Largest) // an endless loop may occur if you do not add this judgment. In this case, you can compress {TMP = A [I]; A [I] = A [Largest]; A [Largest] = TMP; I = largest; // actually, it depends on the amount of recursion changes each time to eliminate recursion} else {break ;}}} // heap creation void buildmaxheap (int * a, int heapsize) {int I = 0; for (I = buffer_size/2; I> 0; I --) {maxheapify (, i, heapsize) ;}}// returns the maximum heap value int heapmaximum (int * A) {return a [1];} // remove and return the int heapextractmax (int * a, int * heapsize) element with the maximum keyword in the heap {int max = 0; int n = * heapsize; if (n <1) {return-1;} max = A [1]; A [1] = A [n ]; * Heapsize = n-1; maxheapify (A, 1, * heapsize); Return Max;} // increase the key value of element x to K, here, K cannot be less than the original keyword value of X void heapincreasekey (int * a, int I, int K) {int TMP = 0; If (k <A [I]) {return;} A [I] = K; while (I> 1 & A [I]> A [I> 1]) {TMP = A [I]; A [I] = A [I> 1]; A [I> 1] = TMP; I = I> 1 ;}} // insert element x into the heap void maxheapinsert (int * a, int * heapsize, int key) {* heapsize + = 1; A [* heapsize] = key-1; // assign the newly added element a value smaller than the key heapincreasekey (A, * heapsize, key);} void output (int *, Int Len) {int I = 1; for (I = 1; I <= Len; I ++) {printf ("% d", a [I]);} printf ("\ n") ;}int main () {int I = 0; int heapsize = 0; int A [buffer_size + 1]; // The first position is a [0]. Therefore, it is easy to calculate the index of a subnode. Memset (A, 0, sizeof (a); srand (unsigned) Time (null); for (I = 1; I <= buffer_size; I ++) {A [I] = rand () % buffer_size;} printf ("randomly generated array:"); output (A, buffer_size); // create the maximum heap buildmaxheap (, buffer_size); printf ("Maximum heap created:"); output (A, buffer_size); // return the maximum keyword element in the heap printf ("return the maximum keyword element in the heap: % d \ n ", heapmaximum (a); // remove and return the element heapsize = buffer_size with the maximum keyword in the heap; printf ("Remove and return the element with the maximum keyword in the heap: % d \ n", heapextractmax (A, & heapsize )); // Add the key value of element x to K. Here, K cannot be smaller than the original key value of X heapincreasekey (A, 4, buffer_size * 2 ); printf ("add the keyword value of element a [4] To buffer_size * 2:"); output (A, heapsize ); // insert element x into the heap maxheapinsert (A, & heapsize, buffer_size * 3); printf ("insert element buffer_size * 3 into the heap :"); output (A, heapsize); System ("pause"); Return 0 ;}