min-priority queue

根据算法导论章节实现。

#include "2.h"#include <stdio.h>int g_heapsize;int g_length;void min_heap_heapify(int *data, int i){int left = 2 * i;int right = 2 * i + 1;int min;if(left <= g_heapsize && data[left] < data[i]){min = left;}else{min = i;}if(right <= g_heapsize && data[right] < data[min]){min = right;}if(min != i){int tmp = data[i];data[i] = data[min];data[min] = tmp;min_heap_heapify(data, min);}}void min_heap_init_length(int length){g_length = length;}void min_heap_build(int *data){g_heapsize = g_length;int i;for(i = g_length / 2; i > 0; i--){min_heap_heapify(data, i);}}void min_heap_decrease_key(int *data, int i, int key){if( key > data[i]){printf("key should not be larger than data[%d]\n", i);return;}data[i] = key;int parent = i / 2;while( i > 1 && data[parent] > key){int tmp = data[i];data[i] = data[parent];data[parent] = tmp;i = parent;parent = i / 2;}}void min_heap_insert(int *data, int key){g_heapsize = g_heapsize + 1;data[g_heapsize] = 1 << 31 - 1;min_heap_decrease_key(data, g_heapsize, key); }int min_heap_extract(int *data){min_heap_build(data);int min = data[1];data[1] = data[g_heapsize];g_heapsize = g_heapsize -1;min_heap_heapify(data, 1);return data[1];}int main(int argc, char **argv){int data[] = {-1, 234, 23, 15, 67, 5, 88, 100, 50};min_heap_init_length(sizeof(data)/sizeof(data[0])-1);int min = min_heap_extract(data);min_heap_insert(data, 4);return 0;}