Time complexity

consider the Java methods:

//assume a.length > 0 static int g(int [] a){ return g (a, 0, a.length-1); }

static int g(int [] a, int i, int j) { if (i == j) return a[i]; int onefourth = (j+1-i) /4; return g(a, i, i+onefourth) + g(a, i+onefourth+1, j); }

(a) what is the asymptotic time complexity of the algorithm described by g(int[]) in function of the input's length. explain with arguments why.

(b) how would the algorithm cost change if you would assign (j+1-i)/5 to the variable onefourth instead of (j+1-i)/4 ?