pro$1.$ When n varies from $3$ to $50,$ TDMA methods are used to determine the displacement of x$1$ in equilibrium to find n versus x$1$ and graph it$.$ Using process C$++$

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I got the c$++$ code for question $1.$ However, I ran the c$++$ code, but an error occurred. I wonder what the problem is$.($Please refer to the picture below$)$

Link to the answer I received : https:$//$www$.$chegg.com$/$homework$-$help$/$questions$-$and$-$answers$/$pro$1-$n$-$varies$-3-50-$tdma$-$methods$-$used$-$determine$-$displacement$-$x$1-$equilibrium$-$find$-$n$-$versus$-$x$-$q$180757385$

The c$++$ code I received:

#include

#include

#include

$//$ Function to perform TDMA $($Thomas Algorithm$)$

void TDMA$($const std::vector& a$,$ const std::vector& b$,$ const std::vector& c$,$ std::vector& d$,$ std::vector& x$)\{$

int n $=$ b$.$size$()$;

std::vector c$\_$star$($n$,0\mathrm{.}0)$;

std::vector d$\_$star$($n$,0\mathrm{.}0)$;

$//$ Modify the coefficients

c$\_$star$[0]=$ c$[0]/$ b$[0]$;

d$\_$star$[0]=$ d$[0]/$ b$[0]$;

for $($int i $=1$; i $$ n; i$++)\{$

double m $=1\mathrm{.}0/($b$[$i$]-$ a$[$i$]*$ c$\_$star$[$i $-1])$;

c$\_$star$[$i$]=$ c$[$i$]*$ m;

d$\_$star$[$i$]=($d$[$i$]-$ a$[$i$]*$ d$\_$star$[$i $-1])*$ m;

$\}$

$//$ Back substitution

x$[$n $-1]=$ d$\_$star$[$n $-1]$;

for $($int i $=$ n $-2$; i $>=0$; i$--)\{$

x$[$i$]=$ d$\_$star$[$i$]-$ c$\_$star$[$i$]*$ x$[$i $+1]$;

$\}$

$\}$

int main$()\{$

$//$ Open a file to write results

std::ofstream outfile$("$results$.$txt$")$;

$//$ Loop over different sizes of the matrix

for $($int n $=3$; n ; $++$n$)\{$

$//$ Initialize vectors for the tridiagonal matrix

std::vector a$($n $-1,-1\mathrm{.}0)$; $//$ Subdiagonal $($a$\_1$ to a$\_\{$n$-1\})$

std::vector b$($n$,2\mathrm{.}0)$; $//$ Main diagonal $($b$\_0$ to b$\_\{$n$-1\})$

std::vector c$($n $-1,-1\mathrm{.}0)$; $//$ Superdiagonal $($c$\_0$ to c$\_\{$n$-2\})$

std::vector d$($n$,1\mathrm{.}0)$; $//$ Right$-$hand side $($d$\_0$ to d$\_\{$n$-1\})$

$//$ Vector to store the solution

std::vector x$($n$,0\mathrm{.}0)$;

$//$ Apply TDMA to solve the system

TDMA$($a$,$ b$,$ c$,$ d$,$ x$)$;

$//$ Output the displacement x$1$

std::cout n $="$ n x$1="$ x$[0]$ std::endl;

outfile $$ n x$[0]$ std::endl;

$\}$

$//$ Close the file

outfile.close$()$;

return $0$;

$\}$