我编写了这段代码，该代码实现了最小生成树的Kruskal算法，当我将其提交给在线法官时会产生分段错误。我认为我已经将分割错误的原因缩小到了对边缘进行排序的部分。仍然，我找不到此代码失败的确切原因。

struct DisjointSet{
    private:
        struct Node{
            int size;
            int repr;
            Node(int rep){
                size = 1;
                repr = rep;
            }
        };
        vector<Node> nodes;
    public:
        int makeSet(){
            nodes.push_back(Node(nodes.size()));
            return nodes.size() - 1;
        }
        int findRepresentative(int ind){
            if(nodes[nodes[ind].repr].size == -1){
                nodes[ind].repr = findRepresentative(nodes[ind].repr);
            }
            return nodes[ind].repr;
        }
        void unionSets(int ind1,int ind2){
            int rep1 = findRepresentative(ind1),rep2 = findRepresentative(ind2);
            if(rep1 != rep2){
                if(nodes[rep1].size < nodes[rep2].size){
                    int t = rep1;
                    rep1 = rep2;
                    rep2 = t;
                }
                nodes[rep1].size += nodes[rep2].size;
                nodes[rep2].size = -1;
                nodes[rep2].repr = rep1;
            }
        }
};

bool compare(const pair<pair<int,int>,int> &p1,const pair<pair<int,int> &p2){
    return (p1.second <= p2.second);
}

int spanningTree(int V,int E,vector<vector<int>> &graph) {
    vector<pair<pair<int,int>> edges;
    for(int i = 0;i < V;i ++){
        for(int j = 0;j < V;j ++){
            if(i <= j){
                if(graph[i][j] != INT_MAX){
                    edges.push_back(make_pair(make_pair(i,j),graph[i][j]));
                }
            }
        }
    }
    sort(edges.begin(),edges.end(),compare);
    DisjointSet d;
    for(int i = 0;i < V;i ++){
        d.makeSet();
    }
    int weight = 0;
    for(int i = 0;i < edges.size();i ++){
        int u = edges[i].first.first,v = edges[i].first.second;
        if(d.findRepresentative(u) != d.findRepresentative(v)){
            d.unionSets(u,v);
            weight += edges[i].second;
        }
    }
    return weight;
}