Question

我正在尝试编写一个代码来查找图表中的循环。但是当我的递归函数返回时，迭代器似乎失去了它的值。这是代码：

#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

vector<int > vec[100]; ///Here i hold the nodes
vector<int > ::iterator it;///Iterator for accessing "vec" elements
int viz[100],n,m;///viz remembers if a node was visited, n is the number of nodes and m the number of edges

void ham(int i)
{
    for(it=vec[i].begin();it!=vec[i].end();it++)
    {
        int j=*it; ///j is just for probing something, no real use
        if(!viz[*it])
        {
            viz[*it]=1; ///the it node is visited
            ham(*it);///I visit this node
            viz[*it]=0;///I consider this node unvisited
        }
    }
    if(i==n)///if i equals n then I print the cycle
    {
        for(int j=1;j<=n;j++)
            if(viz[j])
                cout<<j<<" ";
        cout<<endl;
        return;
    }
}

int main()
{
    ifstream fin("graf.in");
    fin>>n>>m;
    for(int i=1;i<=m;i++)///reading the input and storing it in "vec"
    {
        int x,y;
        fin>>x>>y;
        vec[x].push_back(y);
        vec[y].push_back(x);
    }
    viz[1]=1;///the first node is already visited
    ham(1);///starting from the first node
    return 0;
}

当我的函数返回时，迭代器获得一个负值。谢谢！

Answer 1

div {
  height: 20px;
  width: 20px;
  transform: translateX(50%) rotate(-30deg);
// you can essentially do everything in the div versus the svg
}

svg {
  height: 100%;
  width: 100%;
  fill: white
}

是一个全局变量。每次递归调用ham函数时，都会使用并覆盖它，因此当ham返回时，迭代器处于错误状态。将迭代器移动到ham函数中，因此每次调用ham时它都有自己的迭代器。

迭代器失去价值

1 个答案: