所以基本上我想在C ++中实现这个Finding all cycles in undirected graphs（唯一的区别是图表是加权的），但是现在这不是我的问题，因为我可以稍后处理它。
我尝试将C＃代码重写为C ++，但我对C ++中的OOP仍然没有信心，而且我不太明白我做错了什么。我使用调试器，我的程序甚至没有进入findNewCycles函数，我也很确定有更多问题，但目前我想知道如何开始。我的Path类的构造函数有问题（至少调试器建议我这个），但我不明白为什么。你能帮我么？这是我的代码：
#include <iostream>
#include <utility>
#include <vector>
#include <algorithm>
using namespace std;
class Graph {
struct Edge {
int vert[2];
double value;
public:
Edge(int vec1, int vec2, double w) {
vert[0] = vec1;
vert[1] = vec2;
value = w;
};
};
struct Path {
vector<int> vertices;
double totalValue;
public:
Path() : totalValue(0) {};
Path(vector<int> v, double tv) : vertices(v), totalValue(tv) {};
Path(const Path &a) {
totalValue = a.totalValue;
vertices = a.vertices;
}
};
int vortexCount, edgeCount, cycleCount;
vector<Path> cycles;
vector<Edge> edges;
void findNewCycles(Path a) {
int n = a.vertices[0];
int x;
Path sub(a);
for(int i = 0; i < edgeCount; i++) {
for(int j = 0; j <=1; j++) {
if (edges[i].vert[j] == n) {
x = edges[i].vert[(j+1)%2];
if (!visited(x, a)) {
sub.totalValue += edges[i].value;
sub.vertices.insert(sub.vertices.begin(), x);
findNewCycles(sub);
}
else if ((a.vertices.size() > 2) && (x == a.vertices[a.vertices.size() - 1])) {
Path normal = normalize(a);
Path inv = invert(normal);
if(isNew(normal) && isNew(inv)) cycles.push_back(normal);
}
}
}
}
}
bool equals(Path a, Path b) {
if((a.vertices.size() == b.vertices.size()) && (a.totalValue == b.totalValue)) {
for (unsigned i=0; i < a.vertices.size(); i++) {
if(a.vertices[i] != b.vertices[i]) return false;
}
return true;
}
else return false;
}
Path invert(Path a) {
Path inverted(a);
reverse(inverted.vertices.begin(), inverted.vertices.end());
return normalize(inverted);
}
Path normalize(Path a) {
Path normalized(a);
vector<int>::iterator smallest = min_element(normalized.vertices.begin(), normalized.vertices.end());
std::rotate(normalized.vertices.begin(), smallest, normalized.vertices.end());
return normalized;
}
bool isNew(Path a) {
for(int i=0; i<cycleCount; i++) {
if(equals(cycles[i], a)) {
return false;
}
}
return true;
}
bool visited(int n, Path a) {
for (unsigned i=0; i < a.vertices.size(); i++) {
if(a.vertices[i] == n) return true;
}
return false;
}
public:
Graph(int size) : vortexCount(size), edgeCount(0), cycleCount(0) {};
~Graph() {};
vector<Edge>::iterator findEdge(int v1, int v2) {
if(v1 == v2 || v1 > vortexCount || v2 > vortexCount) return edges.end();
vector<Edge>::iterator iter;
for(iter = edges.begin(); iter != edges.end(); ++iter) {
if(iter->vert[0] == v1 && iter->vert[1] == v2) return iter;
if(iter->vert[1] == v1 && iter->vert[0] == v2) return iter;
}
return edges.end();
}
bool addEdge(int v1, int v2, double value) {
if(v1 == v2 || v1 > vortexCount || v2 > vortexCount) return false;
vector<Edge>::iterator p = findEdge(v1, v2);
if(p != edges.end()) {
p->value = value;
}
else {
Edge edge(v1, v2, value);
edges.push_back(edge);
edgeCount++;
}
return true;
}
void runCycleSearch() {
for (int i = 0; i < edgeCount; i++) {
for (int j = 0; j < 2; j++) {
cout << i << " " << j;
Path searchPath;
searchPath.vertices.push_back(edges[i].vert[j]);
findNewCycles(searchPath);
}
}
for(int i=0; i<cycleCount; i++) {
for(unsigned j=0; j<cycles[i].vertices.size(); j++) {
cout << cycles[i].vertices[j] << " ";
}
cout << cycles[i].totalValue;
}
}
};
int main() {
int n, v1, v2;
double val;
bool control = true;
cin >> n;
Graph graph(n);
while(control) {
cin >> v1;
if(v1 == -1) break;
cin >> v2 >> val;
control = graph.addEdge(v1, v2, val);
}
graph.runCycleSearch();
}
答案 0 :(得分：0)
你确定你已经离开了while循环吗？
尝试在阅读输入后添加此行：
cout << "v1=" << v1 << ", v2=" << v2 << " val=" << val << endl;
并将while (control)更改为
for (int i=0; i < n; i++)
答案 1 :(得分：0)
我发现了第一个错误。找到循环时，您没有更新cycleCount变量。即
else if ((a.vertices.size() > 2) && (x == a.vertices[a.vertices.size() - 1])) {
Path normal = normalize(a);
Path inv = invert(normal);
if(isNew(normal) && isNew(inv)) cycles.push_back(normal);
}
替换为
else if ((a.vertices.size() > 2) && (x == a.vertices[a.vertices.size() - 1])) {
Path normal = normalize(a);
Path inv = invert(normal);
if (isNew(normal) && isNew(inv)) {
cycleCount++;
cycles.push_back(normal);
}
}
我的建议仅针对此错误：完全删除edgeCount和cycleCount，您可以使用cycles.size()和edges.size()
此外，我将打印更改为cout：
in void runCycleSearch() function:
cout << "Cycles:\n";
for (int i = 0; i<cycleCount; i++) {
for (unsigned j = 0; j<cycles[i].vertices.size(); j++) {
cout << cycles[i].vertices[j] << " ";
}
cout << cycles[i].totalValue;
cout << "\n";
}
但是这段代码非常粗心并且充满了错误。例如，案例
4
1 2 0
2 3 0
3 4 0
1 4 0
返回
Cycles:
1 2 4 0
1 3 2 0
2 4 3 0
1 4 3 0
我可以继续更正此代码，但对我来说，从头开始重写更容易:)有很多问题：
isNew(Path a)您需要将其替换为可能的引用。