can't get rid of SIGSEGV error in this code,please help

 #include<iostream>
using namespace std;
int c[50],a[100][100];
int main()
{
int z=0,k=0,t,n,i,j;
cin>>t;
while(z<t)
{
cin>>n;
for(i=0;i<n;++i)
for(j=0;j<=i;++j)
{
cin>>a[i][j];
}
for(i=0;i<n;++i)
for(j=0;j<n;++j)
{
if(i<j)
a[i][j]=0;
}
for(i=n-1;i>=0;--i)
for(j=0;j<n;j=j+1)
{
if(a[i][j]>a[i][j+1])
a[i-1][j]=a[i-1][j]+a[i][j];
else
a[i-1][j]=a[i-1][j]+a[i][j+1];
}
c[k]=a[0][0];
++k;
++z;
}
k=0;
while(k<t)
{
cout<<c[k]<<endl;
k=k+1;
}
return 0;
}