@Test
public void testGetSum() {
int n = 2000;
long[] A = randomArray(n);
FenwickTree fw = fenwickTree(A);
for (int i = 0, cumul = 0; i < A.length; i++) {
cumul += A[i];
assertEquals(cumul, fw.getSum(i + 1));
}
}
@Test
public void testFindHigherValueIndex() {
int n = 500;
long[] A = randomArray(n);
FenwickTree fw = fenwickTree(A);
for (int i = 0; i < A.length; i++) {
long sum = fw.getSum(i + 1);
assertEquals(findHigherSumIndex(A, sum) + 1, fw.findHigherSumIndex(sum));
}
long sum = 10000000;
assertEquals(findHigherSumIndex(A, sum) + 1, fw.findHigherSumIndex(sum));
sum = -10000000;
assertEquals(findHigherSumIndex(A, sum) + 1, fw.findHigherSumIndex(sum));
}