Lines 50-53:

it[l].sum = it[id].sv*(mid-st+1);
it[r].sum = it[id].sv*(se-mid);
it[l].ic = it[r].ic = 0;
it[id].sv = 0;

You set the left and right child's sums, but then you don't propagate it[id].sv to it[l].sv and it[r].sv, so any children underneath the left and right children don't get set properly.