1、稀疏矩陣
10年積累的做網(wǎng)站、成都網(wǎng)站建設(shè)經(jīng)驗,可以快速應(yīng)對客戶對網(wǎng)站的新想法和需求。提供各種問題對應(yīng)的解決方案。讓選擇我們的客戶得到更好、更有力的網(wǎng)絡(luò)服務(wù)。我雖然不認識你,你也不認識我。但先網(wǎng)站制作后付款的網(wǎng)站建設(shè)流程,更有羅定免費網(wǎng)站建設(shè)讓你可以放心的選擇與我們合作。有一個稀疏因子,這是節(jié)省空間的一種存儲方式。
2、鄰接表
以鄰接矩陣存儲圖結(jié)構(gòu)的話,當實際邊數(shù)遠遠小于圖的大邊數(shù)時,將會存儲很多0,勢必造成存儲空間的巨大浪費;這時,就必須將鄰接矩陣該用為鄰接表;將鄰接矩陣各行組織為一個單鏈表,類哈希的存儲結(jié)構(gòu)。
存儲結(jié)構(gòu)(控制頭):
int maxVertices; //大頂點數(shù) int curVertices; //當前頂點數(shù) int curEdges; //當前邊數(shù) templateclass Edge{ //邊的存儲結(jié)構(gòu) public: Edge(int num) : dest(num), link(NULL){} public: int dest; //是另一個頂點的下標 Edge *link; }; template class Vertex{ //頂點的存儲結(jié)構(gòu) public: Type data; //存放的頂點 Edge *adj; }; Vertex *vertexTable; //指向頂點的指針,是申請數(shù)組用的
存儲模型:
3、核心方法
均由C++實現(xiàn),無向圖的鄰接表;
(1)、刪除邊(是鏈表的刪除操作,相對簡單):
bool removeEdge(const Type &v1, const Type &v2){ //刪除邊 int i = getVertexIndex(v1); int j = getVertexIndex(v2); if(i==-1 || j==-1){ //保證頂點的保存在 return false; } //v1-->v2 Edge*p = vertexTable[i].adj; if(p == NULL){ //判斷有沒有邊 return false; } if(p->link == NULL && p->dest == j){ //刪除的是第一個邊,其后沒有邊了; vertexTable[i].adj = NULL; delete p; }else if(p->dest == j){ //刪除的是第一個邊,并且其后還有邊 vertexTable[i].adj = p->link; delete p; }else{ while(p->link != NULL){ if(p->link->dest == j){ Edge *q = p->link; p->link = q->link; delete q; } p = p->link; } } //v2-->v1 Edge *s = vertexTable[j].adj; if(s == NULL){ //判斷有沒有邊 return false; } if(s->link == NULL && s->dest == i){ //刪除的是第一個邊,其后沒有邊了; vertexTable[j].adj = NULL; delete s; curEdges--; return false; }else if(s->dest == i){ //刪除的是第一個邊,并且其后還有邊 vertexTable[j].adj = s->link; delete s; curEdges--; return true; }else{ while(s->link != NULL){ if(s->link->dest == i){ Edge *q = s->link; s->link = q->link; delete q; curEdges--; return true; } s = s->link; } } return true; }
(2)、刪除頂點:
這個算法相對復(fù)雜,但是思路比較清晰:
i>、首先找到要刪除的頂點,將其后上的邊所對應(yīng)的邊和這個邊都得刪除;
ii>、將最后一個頂點的data和adj都覆蓋到這個地方;
iii>、找到其后邊上的dest,更改為當下位置的下標;
大致模型如下:
bool removeVertex(const Type &v){ //刪除頂點 int i = getVertexIndex(v); if(i == -1){ return false; } Edge*p = vertexTable[i].adj; //先刪除邊上的dest和此邊 while(p != NULL){ vertexTable[i].adj = p->link; int k = p->dest; Edge *q = vertexTable[k].adj; if(q->dest == i){ vertexTable[k].adj = q->link; delete q; }else{ while(q->link != NULL && q->link->dest != i){ q = q->link; } Edge *t = q->link; q->link = t->link; delete t; } delete p; p = vertexTable[i].adj; curEdges--; } curVertices--; //下面實行覆蓋,指針和最后的那個頂點的adj相等; vertexTable[i].data = vertexTable[curVertices].data; vertexTable[i].adj = vertexTable[curVertices].adj; vertexTable[curVertices].adj = NULL; int k = curVertices; p = vertexTable[i].adj; while(p != NULL){ //修改其它頂點的dest. Edge *s = vertexTable[p->dest].adj; while(s != NULL){ if(s->dest == k){ s->dest = i; break; } s = s->link; } p = p->link; } return true; }
4、鄰接表完整代碼、測試代碼、測試結(jié)果
(1)完整代碼(用的是繼承,方便寫其它的存儲結(jié)構(gòu)代碼):
#ifndef _GRAPH_H_ #define _GRAPH_H_ #includeusing namespace std; #define VERTEX_DEFAULT_SIZE 10 template class Graph{ public: bool isEmpty()const{ return curVertices == 0; } bool isFull()const{ if(curVertices >= maxVertices || curEdges >= curVertices*(curVertices-1)/2) return true; //圖滿有2種情況:(1)、當前頂點數(shù)超過了大頂點數(shù),存放頂點的空間已滿 return false; //(2)、當前頂點數(shù)并沒有滿,但是當前頂點所能達到的邊數(shù)已滿 } int getCurVertex()const{ return curVertices; } int getCurEdge()const{ return curEdges; } public: virtual bool insertVertex(const Type &v) = 0; //插入頂點 virtual bool insertEdge(const Type &v1, const Type &v2) = 0; //插入邊 virtual bool removeVertex(const Type &v) = 0; //刪除頂點 virtual bool removeEdge(const Type &v1, const Type &v2) = 0; //刪除邊 virtual int getFirstNeighbor(const Type &v) = 0; //得到第一個相鄰頂點 virtual int getNextNeighbor(const Type &v, const Type &w) = 0; //得到下一個相鄰頂點 public: virtual int getVertexIndex(const Type &v)const = 0; //得到頂點下標 virtual void showGraph()const = 0; //顯示圖 protected: int maxVertices; //大頂點數(shù) int curVertices; //當前頂點數(shù) int curEdges; //當前邊數(shù) }; template class Edge{ //邊的存儲結(jié)構(gòu) public: Edge(int num) : dest(num), link(NULL){} public: int dest; Edge *link; }; template class Vertex{ //頂點的存儲結(jié)構(gòu) public: Type data; Edge *adj; }; template class GraphLnk : public Graph { #define maxVertices Graph ::maxVertices //因為是模板,所以用父類的數(shù)據(jù)或方法都得加上作用域限定符 #define curVertices Graph ::curVertices #define curEdges Graph ::curEdges public: GraphLnk(int sz = VERTEX_DEFAULT_SIZE){ maxVertices = sz > VERTEX_DEFAULT_SIZE ? sz : VERTEX_DEFAULT_SIZE; vertexTable = new Vertex [maxVertices]; for(int i = 0; i < maxVertices; i++){ vertexTable[i].data = 0; vertexTable[i].adj = NULL; } curVertices = curEdges = 0; } public: bool insertVertex(const Type &v){ if(curVertices >= maxVertices){ return false; } vertexTable[curVertices++].data = v; return true; } bool insertEdge(const Type &v1, const Type &v2){ int v = getVertexIndex(v1); int w = getVertexIndex(v2); if(v==-1 || w==-1){ return false; } Edge *p = vertexTable[v].adj; while(p != NULL){ //這里主要判斷邊是否已經(jīng)存在 if(p->dest == w){ //無向圖,判斷一邊即可; return false; } p = p->link; } //v1-->v2 //采用頭插 Edge *s = new Edge (w); s->link = vertexTable[v].adj; vertexTable[v].adj = s; //v2-->v1 //采用頭插 Edge *q = new Edge (v); q->link = vertexTable[w].adj; vertexTable[w].adj = q; curEdges++; return true; } bool removeVertex(const Type &v){ int i = getVertexIndex(v); if(i == -1){ return false; } Edge *p = vertexTable[i].adj; while(p != NULL){ vertexTable[i].adj = p->link; int k = p->dest; Edge *q = vertexTable[k].adj; if(q->dest == i){ vertexTable[k].adj = q->link; delete q; }else{ while(q->link != NULL && q->link->dest != i){ q = q->link; } Edge *t = q->link; q->link = t->link; delete t; } delete p; p = vertexTable[i].adj; curEdges--; } curVertices--; //下面實行覆蓋 vertexTable[i].data = vertexTable[curVertices].data; vertexTable[i].adj = vertexTable[curVertices].adj; vertexTable[curVertices].adj = NULL; int k = curVertices; p = vertexTable[i].adj; while(p != NULL){ Edge *s = vertexTable[p->dest].adj; while(s != NULL){ if(s->dest == k){ s->dest = i; break; } s = s->link; } p = p->link; } return true; } bool removeEdge(const Type &v1, const Type &v2){ int i = getVertexIndex(v1); int j = getVertexIndex(v2); if(i==-1 || j==-1){ //保證頂點的保存在 return false; } //v1-->v2 Edge *p = vertexTable[i].adj; if(p == NULL){ //判斷有沒有邊 return false; } if(p->link == NULL && p->dest == j){ //刪除的是第一個邊,其后沒有邊了; vertexTable[i].adj = NULL; delete p; }else if(p->dest == j){ //刪除的是第一個邊,并且其后還有邊 vertexTable[i].adj = p->link; delete p; }else{ while(p->link != NULL){ if(p->link->dest == j){ Edge *q = p->link; p->link = q->link; delete q; } p = p->link; } } //v2-->v1 Edge *s = vertexTable[j].adj; if(s == NULL){ //判斷有沒有邊 return false; } if(s->link == NULL && s->dest == i){ //刪除的是第一個邊,其后沒有邊了; vertexTable[j].adj = NULL; delete s; curEdges--; return false; }else if(s->dest == i){ //刪除的是第一個邊,并且其后還有邊 vertexTable[j].adj = s->link; delete s; curEdges--; return true; }else{ while(s->link != NULL){ if(s->link->dest == i){ Edge *q = s->link; s->link = q->link; delete q; curEdges--; return true; } s = s->link; } } return true; } int getFirstNeighbor(const Type &v){ int i = getVertexIndex(v); if(i != -1){ Edge *p = vertexTable[i].adj; if(p != NULL){ return p->dest; } } return -1; } int getNextNeighbor(const Type &v, const Type &w){ int i = getVertexIndex(v); int j = getVertexIndex(w); if(i==-1 || j==-1){ return -1; } Edge *p = vertexTable[i].adj; while(p != NULL){ if(p->dest == j && p->link != NULL){ return p->link->dest; } p = p->link; } return -1; } public: int getVertexIndex(const Type &v)const{ for(int i = 0; i < curVertices; i++){ if(vertexTable[i].data == v){ return i; } } return -1; } void showGraph()const{ for(int i = 0; i < curVertices; i++){ cout< "; Edge *p = vertexTable[i].adj; while(p != NULL){ cout< dest<<"-->"; p = p->link; } cout<<"Nul. "< *vertexTable; //指向頂點的指針,是申請數(shù)組用的 }; #endif
(2)、測試代碼:
#include"Graph.h" int main(void){ GraphLnkgl; gl.insertVertex('A'); gl.insertVertex('B'); gl.insertVertex('C'); gl.insertVertex('D'); gl.insertEdge('A','B'); gl.insertEdge('A','D'); gl.insertEdge('B','C'); gl.insertEdge('C','D'); gl.showGraph(); cout< (3)、測試結(jié)果:
測試的圖:
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文章題目:圖的存儲之鄰接表-創(chuàng)新互聯(lián)
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