50 lines
978 B
C
50 lines
978 B
C
#include "heap.h"
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void heap_sift_up(struct heap_entry * e, int ix)
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{
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while (ix > 0) {
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int parent = (ix - 1) / 2;
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if (e[parent].key < e[ix].key) {
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// swap parent and ix
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struct heap_entry tmp = e[parent];
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e[parent] = e[ix];
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e[ix] = tmp;
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ix = parent;
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} else {
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return;
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}
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}
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}
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void heap_append(struct heap_entry * e, int * heap_length, int key, int value)
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{
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int ix = *heap_length;
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e[ix].key = key;
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e[ix].value = value;
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heap_sift_up(e, ix);
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(*heap_length) += 1;
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}
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int heap_find(struct heap_entry * e, int length, int ix, int key)
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{
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if (e[ix].key == key)
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return ix;
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int child_l = 2 * ix + 1;
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int child_r = 2 * ix + 2;
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if (child_r < length && e[child_r].key >= key) {
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int i = heap_find(e, length, child_r, key);
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if (i >= 0)
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return i;
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}
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if (child_l < length && e[child_l].key >= key) {
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int i = heap_find(e, length, child_l, key);
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if (i >= 0)
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return i;
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}
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return -1;
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}
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