Rcpp maximum value by removing several element

  c++, r, rcpp, rcpp11

I’m trying to write down the distance function which calculate the maximum distance between each rows of matrix, however, before calculate the maximum value, I need to remove certain element, the question is posted in the code.

How can I accomplish it in an efficient way?

#include <Rcpp.h>
Rcpp::NumericMatrix Mydist (const Rcpp::NumericMatrix & x){
unsigned int ans = x.nrow(), i = 0, j = 0;
double d;
Rcpp::NumericMatrix out(ans,ans);

for (i = 0; i < outrows - 1; i++){
Rcpp::NumericVector temp = x.row(i);
for (j = i + 1; j < ans ; j ++){
  # here, I need to remove the i and j element in the vector temp-x.row(j) before I can do 
  # the abs() and max(), but i dont know 
  # how to do it efficiently?
  d = max(abs(temp-x.row(j)));
 return out;

Source: Windows Questions C++