Split an Array Like below

Question

This is different than previous uploaded question please see carefully.

I have one array called ans[i].

ans[i]={1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16} //n no.of inputed element.Not fix array

and i want to split in group of 3 and stored it in array.

 

Like this if x=2 the it should store the summation of 1+4+7+10+13..like below.

res[0]= 35 //1+4+7+10+13

res[1]=40 //2+5+8+11+14

res[2]=45 //3+6+9+12+15

 

if x=3 then,

res[0]=1+5+9+13

res[1]=2+6+10+14

res[2]=3+7+11+15

res[3]=4+8+12+16 

 

if x=1 then

 res[0]=1+3+5+7+9+11+13+15 

 res[2]=2+4+6+8+10+12+14+16

 

if x=4,5... for n no of input for n size of an array.

please give code for this.