Dijkstra改进算法C语言

/*9-10(b)-12-13-20.26.c -- 第九章第十题(b)*/#include <stdio.h>#include <stdlib.h>#include "binary_heap.h"int main (void) ;int new_dijkstra (const Adjacenty_List * padj, const Hash_Table * const pht, const int start) ;int main (void){Adjacenty_List adj ;Hash_Table ht ;int capacity = 5 ;Initialize_H (&ht, capacity * 2) ;Initialize_A (&adj, capacity) ;InitializeALine_A (&adj, &ht, 0, 's', 0, 4, 'a', 2, 'd', 3) ;InitializeALine_A (&adj, &ht, 1, 'a', 0, 2, 'b', 2) ;InitializeALine_A (&adj, &ht, 2, 'b', 0, 2, 'c', 2) ;InitializeALine_A (&adj, &ht, 3, 'c', 0, 2, 'd', 2) ;InitializeALine_A (&adj, &ht, 4, 'd', 0, 2, 'c', 3) ;new_dijkstra (&adj, &ht, 0) ;PrintAdjacenty_List_A (&adj, &ht) ;Release_H (&ht) ;Release_A (&adj) ;return 0 ;}int new_dijkstra (const Adjacenty_List * padj, const Hash_Table * const pht, const int start){Binary_Heap bh ;Vertex * v ;Adjoin_To_Vertex * w ;int capacity = (*padj) -> capacity, i, v_index, w_index ;int * count ;count = (int *) calloc (sizeof (int), capacity) ;if (NULL == count)return 0 ;Initialize_B (&bh, capacity * 2) ;(*padj) -> list[start].dist = 0 ;for (i = 0; i < capacity; i++)Insert_B (&bh, (*padj) -> list + i) ;while (1){do{v = DeleteMin_B (&bh) ;if (NEGATIVEINFINITY == v -> dist)break ;}while (TRUE == (*pht) -> lists[v -> hash_value].be_deleted);if (NEGATIVEINFINITY == v -> dist)break ;(*pht) -> lists[v -> hash_value].be_deleted = TRUE ;v -> known = TRUE ;w = v -> adjoin_to ;v_index = (*pht) -> lists[v -> hash_value].index_in_adjacenty_list ;while (w){w_index = (*pht) -> lists[w -> hash_value].index_in_adjacenty_list ;if (FALSE == (*padj) -> list[w_index].known){if (v -> dist + w -> cvw < (*padj) -> list[w_index].dist){count[w_index] = count[v_index] + 1 ;(*padj) -> list[w_index].dist = v -> dist + w -> cvw ;Insert_B (&bh, (*padj) -> list + w_index) ;(*padj) -> list[w_index].path = (*pht) -> lists[v -> hash_value].name ;}else if (v -> dist + w -> cvw == (*padj) -> list[w_index].dist){if (count[v_index] + 1 < count[w_index]){count[w_index] = count[v_index] + 1 ;(*padj) -> list[w_index].path = (*pht) -> lists[v -> hash_value].name ;}}}w = w -> next ;}}free (count) ;Release_B (&bh) ;return 1 ;} 这个例程,会在多条相同最短路径中选出边数最少的路径.只是改变path域即可在遍历的时候访问到边数少的路径.核心的思想,就是建立一个数组,存放从出发点到当前顶点的最短路径边数.通过每次查看最短路径相同的情况, 即d_v + cvw = d_w.时,如果 Count[v] + 1 < Count[w]时,就执行 Count[w] = Count[v] + 1, 同时 w -> path = c. 就是这样吧,自己想出来的答案跟这个比较贴边.希望,我能记住.或者,消化得好一些.