前面已经说了图的深度优先遍历算法,是用递归实现的,而在这里就讲一下用非递归实现,需要借助栈:
算法思想:
1. 栈初始化
2. 输出起始顶点,起始顶点改为“已访问”标志,将起始顶点进栈
3. 重复下列操作直到栈为空:
3.1 取栈顶元素顶点
3.2 栈顶元素顶点存在未被访问过的邻接点w,则:
3.2.1 输出顶点w
3.2.2 将顶点w改为“已访问”标志
3.2.3 将顶点w进栈
3.3 否则,当前顶点出栈
非递归实现深度优先遍历(邻接链表法)
static void orther_dfs(TLGraph* tGraph, int v, int visited[], LGraph_Printf* pFunc)
{
LinkStack* stack = LinkStack_Create();
LinkStack_Push(stack, tGraph->v + v);
while(!LinkStack_Empty(stack))
{
int w = (LVertex**)LinkStack_Top(stack) - tGraph->v;
LinkStack_Pop(stack);
if(!visited[w])
{
int i = 0;
pFunc(tGraph->v[w]);
visited[w] = 1;
for(i=0; i<LinkList_Length(tGraph->la[v]); i++)
{
if(!visited[i])
{
LinkStack_Push(stack, tGraph->v + i);
}
}
}
}
LinkStack_Destroy(stack);
}
void LGraph_DFS_Orther(LGraph* graph, int v, LGraph_Printf* pFunc)
{
TLGraph* tGraph = (TLGraph*)graph;
int* visited = NULL;
int condition = (NULL != tGraph);
condition = condition && (0 <= v) && (v < tGraph->count);
condition = condition && (NULL != pFunc);
condition = condition && (NULL != (visited = (int*)calloc(tGraph->count, sizeof(int))));
if(condition)
{
int i = 0;
orther_dfs(tGraph, v, visited, pFunc);
for(i=0; i<tGraph->count; i++)
{
if(!visited[i])
{
orther_dfs(tGraph, i, visited, pFunc);
}
}
printf("\n");
}
free(visited);
}
非递归实现深度优先遍历(邻接矩阵法)
static void orther_dfs(TMGraph* tGraph, int v, int visited[], MGraph_Printf* pFunc)
{
LinkStack* stack = LinkStack_Create();
LinkStack_Push(stack, tGraph->v + v);
while(!LinkStack_Empty(stack))
{
int w = (MVertex**)LinkStack_Top(stack) - tGraph->v;
LinkStack_Pop(stack);
if(!visited[w])
{
int i = 0;
pFunc(tGraph->v[w]);
visited[w] = 1;
for(i=0; i<LinkList_Length(tGraph->count); i++)
{
if((0!=tGraph->matrix[v][i]) && (!visited[i]))
{
LinkStack_Push(stack, tGraph->v + i);
}
}
}
}
LinkStack_Destroy(stack);
}
void MGraph_DFS_Orther(MGraph* graph, int v, MGraph_Printf* pFunc)
{
TMGraph* tGraph = (TMGraph*)graph;
int* visited = NULL;
int condition = (NULL != tGraph);
condition = condition && (0 <= v) && (v < tGraph->count);
condition = condition && (NULL != pFunc);
condition = condition && (NULL != (visited = (int*)calloc(tGraph->count, sizeof(int))));
if(condition)
{
int i = 0;
orther_dfs(tGraph, v, visited, pFunc);
for(i=0; i<tGraph->count; i++)
{
if(!visited[i])
{
orther_dfs(tGraph, i, visited, pFunc);
}
}
printf("\n");
}
free(visited);
}