163: Missing Ranges

Given a sorted integer array where the range of elements are [0, 99] inclusive, return its missing ranges.

For example, given [0, 1, 3, 50, 75],

return [“2”, “4->49”, “51->74”, “76->99”]

public class Solution {
    public List<String> findMissingRanges(int[] vals, int start, int end) {
        List<String> ranges = new ArrayList<String>();
        int prev = start - 1;
        for (int i=0; i<=vals.length; ++i) {
            int curr = (i==vals.length) ? end + 1 : vals[i];
            if ( cur-prev>=2 ) {
                ranges.add(getRange(prev+1, curr-1));
            }
            prev = curr;
        }
        return ranges;
    }

    private String getRange(int from, int to) {
        return (from==to) ? String.valueOf(from) : from + "->" + to;
    }
}