改良　変数名など変更

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

template<class T> class retu {
public:
int m; vector< vector<T> > *vec;
T& operator[](int n) { return (*vec)[m][n]; } };

template<class T> class nijyu_test {
vector< vector<T> > vec;
retu<T> ret;
public:
nijyu_test(int x,int y) {
vec = vector< vector<T> >( x, vector<T>(y) ); ret.vec = &vec; }
retu<T>& operator[](int m) { ret.m = m; return ret; } };

int main () {
nijyu_test<int> A(3,5);
int m,n;
for(m=0;m<3;m++) for(n=0;n<5;n++) A[m][n] = (m+1)*(n+1);
for(m=0;m<3;m++) {
for(n=0;n<5;n++) printf("%3d", A[m][n]);
printf("\n"); }}