在spoj上提交时的运行时错误（SIGSEGV）

Question

在SPOJ上提交此代码时出现运行时错误（SIGSEGV）错误。我清除了向量并初始化了所有变量，但仍然得到了错误。这段代码有什么问题？

#include<iostream>
#include<vector>
using namespace std;

vector<int> even_greater_increment(vector<int> num,int mid1,int mid2){
    int bigindex=0,smallindex=0;
    if(num[mid1]==num[mid2]){
        return num;
    }
    if(num[mid1]>num[mid2]){
        bigindex=mid1;
        smallindex=mid2;
    }
    else{
        bigindex=mid2;
        smallindex=mid1;
    }
    while(num[smallindex]!=num[bigindex]){
        num[smallindex]++;
    }
    return num;
}

bool check9(vector<int> num,int vlen){

    for(int i=0;i<vlen;i++){
        if(num[i]==9){
            continue;
        }
        else{
            return false;
        }
    }
    return true;
}

int nine(vector<int> num,int vlen){

    vlen=vlen+1;

    num[0]=1;
    cout<<num[0];
    for(int i=1;i<vlen-1;i++){
        num[i]=0;
        cout<<num[i];
    }
    num[vlen-1]=1;
    cout<<num[vlen-1];
    return 0;
}

vector<int> increment9(vector<int> num,int mid1,int mid2,int vlen){
    int l=mid1,k=mid2;
    do{
        l--;k++;
    }while((l>=0&&k<=(vlen-1))&&(num[l]==9&&num[k]==9));

    num[l]++;
    num[k]++;
    for(int i=l+1;i<k;i++){
        num[i]=0;
    }
    return num;
}

vector<int> incrementmiddle(vector<int> num,int mid1,int mid2,int vlen){
    if(num[mid1]==9&&num[mid2]==9){
        num=increment9(num,mid1,mid2,vlen);
        return num;
    }
    if(mid1==mid2){//odd implementation
        num[mid1]=num[mid1]+1;
    }
    else{//even implementation
        num=even_greater_increment(num,mid1,mid2);
    }
    return num;
}

int println(vector<int> r,int vlen){
    for(int p=0;p<vlen;p++){
        cout<<r[p];
    }
}

bool comp(const vector<int>& v1, const vector<int>& v2) {
    if (v1.size() != v2.size()) 
        return v1.size() < v2.size();
    for (int i = 0; i < v1.size(); i++)
        if (v1[i] != v2[i])
            return v1[i] < v2[i];
    return false;
}

int palindrome(){
    int length=0;
    char ch[7];
    cin>>ch;
    for(int i=0;ch[i]!='\0';i++){
        length++;
    }

    vector<int> num;
    vector<int> temp;
    for(int j=0;j<length;j++){

        int a= ch[j] - '0';
        num.push_back(a);
    }
    int vlen=num.size();
    int mid1=0,mid2=0;
    if(vlen==1){
        cout<<num[0]<<endl;
        return 0;
    }
    if(vlen==2){
        mid1=0;mid2=1;
        int bigindex,smallindex;
        if(num[mid1]>num[mid2]){
            bigindex=mid1;
            smallindex=mid2;
        }
        else{
            bigindex=mid2;
            smallindex=mid1;
        }
        num[smallindex]=num[bigindex];
        println(num,2);
        return 0;
    }

    if(vlen%2==0){
        mid2=vlen/2;
        mid1=mid2-1;
    }
    else{
        mid1=mid2=vlen/2;
    }
    temp=num;

    if(mid1==mid2){
        int y=mid1;
        //for odd implementation
        for(int j=0;j<mid1;j++){
            ++y;
            num[y]=num[j];

        }
        //num contains palindrome and temp contains original

        if(comp(temp,num)){
            println(num,vlen);
            return 0;
        }//printing the number if the palindrome is greater than the input number

        else{
            if(check9(num,vlen)){
                nine(num,vlen);

                return 0;
            }

            num=incrementmiddle(num,mid1,mid2,vlen);
            println(num,vlen);
            return 0;
        }

    }
    else{//even implementation
        int h=vlen-1;
        for(int b=0;b<mid1;b++){
            num[h]=num[b];
            h--;
        }

        if(comp(temp,num)){

            num=even_greater_increment(num,mid1,mid2);
            println(num,vlen);
            return 0;
        }//printing the number if the palindrome is greater than the input number

        else{

            if(check9(num,vlen)){
                nine(num,vlen);

                return 0;
            }
            num=incrementmiddle(num,mid1,mid2,vlen);
            println(num,vlen);
            return 0;
        }
    }

    num.clear();
    temp.clear();

}

int main(){
    int test=0;
    cin>>test;
testcase:
    for(int f=0;f<test;f++){
        palindrome();
        cout<<endl;
    }
}

它实际上需要一个数字并打印下一个小回文。 逻辑和一切都是正确的。它在编译器和ideone中工作正常。 请帮忙。我真的很想接受这个问题，因为我花了5个多小时编写逻辑。