868.java

class Solution {
    public int binaryGap(int N) {
        int last = -1, ans = 0;
        for (int i = 0; i < 32; ++i)
            if (((N >> i) & 1) > 0) {
                if (last >= 0)
                    ans = Math.max(ans, i - last);
                last = i;
            }

        return ans;
    }
}