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一步一步学数据结构之n--n（图遍历--深度优先遍历--非递归实现）

2013-08-17 12:52 483 查看

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);
}

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标签： 前序遍历后序遍历图的遍历图深度优先遍历

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