Reversing vectors in a vector error troubleshoot-CodePudding

vector<vector<string>> Reverse(vector<vector<string>> a){
    vector<string> dd;
    for(int i = 0; i < a.size()/2; i  ){
        dd = a[i];
        a[i] = a[-1*(i) - 1];
        a[-1*(i) - 1] = dd;
    }
    return a;
}

I want to make a Reverse function that reverses vectors in a vector but i get and error:

libc abi: terminating with uncaught exception of type std::bad_alloc: std::bad_alloc terminating with uncaught exception of type std::bad_alloc: std::bad_alloc

CodePudding user response：

You are trying to access negative positions in a vector. Positions starts from 0 to vector.size(). It's very bad what you are doing.You are getting a matrix and try to transform it in a vector? You should review your code. Maybe you meant something like this?

vector<vector<string>> reverseRows(vector<vector<string>> a){
    for(int i=0;i<a.size();i  ){
        for(int j=0;j<a[i].size()/2;i  ){
            string temp=a[i][j];
            a[i][j]=a[i][a[i].size()-j-1];
            a[i][a[i].size()-j-1]=temp;
        }
    }
    return a;
}

vector<vector<string>> reverseMatrix(vector<vector<string>> a){
    for(int i=0;i<a.size()/2;i  ){
            vector<string> temp=a[i][j];
            a[i][j]=a[i][a[i].size()-j-1];
            a[i][a[i].size()-j-1]=temp;
    }
return a;
}

CodePudding user response：

Don't reinvent the wheel:

#include <vector>
#include <algorithm>

std::vector<std::vector<std::string>> reverseInner(std::vector<std::vector<std::string>> a) {
  for_each(begin(a),end(a),[](auto& v) { reverse(begin(v),end(v)); });
  return a;
}

std::vector<std::vector<std::string>> reverseOuter(std::vector<std::vector<std::string>> a) {
  reverse(begin(a),end(a));
  return a;
}