Cracking the Coding Interview, 4 Edition - 150 Programming Interview Questions and Solutions

Solutions to Chapter 5 | Bit Manipulation
1 int findMissing(ArrayList array) {
2 return findMissing(array, BitInteger.INTEGER_SIZE - 1);
3 }
4
5 int findMissing(ArrayList input, int column) {
6 if (column < 0) { // Base case and error condition
7 return 0;
8 }
9 ArrayList oddIndices = new ArrayList();
10 ArrayList evenIndices = new ArrayList();
11 for (BitInteger t : input) {
12 if (t.fetch(column) == 0) {
13 evenIndices.add(t);
14 } else {
15 oddIndices.add(t);
16 }
17 }
18 if (oddIndices.size() >= evenIndices.size()) {
19 return (findMissing(evenIndices, column - 1))