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”]

//https://discuss.leetcode.com/topic/10681/my-concise-java-accepted-solution

public class Solution {

public List<String> findMissingRanges(int[] A, int lower, int upper) {

List<String> result = new ArrayList<String>();

int pre = lower - 1;

for(int i = 0 ; i <= A.length; i++){

int after = i == A.length ? upper + 1 : A[i];

if(pre + 2 == after){

result.add(String.valueOf(pre + 1));

}else if(pre + 2 < after){

result.add(String.valueOf(pre + 1) + "->" + String.valueOf(after - 1));

}

pre = after;

}

return result;

}

}

//////////////////////////////////////

public class Solution {

public List<String> findMissingRanges(int[] nums, int lower, int upper) {

List<String> res = new LinkedList<String>();

int l = lower;

for (int i = 0; i <= nums.size(); ++i) {

int r = (i < nums.length && nums[i] <= upper) ? nums[i] : upper + 1;

if (l == r) {

++l;

} else if (r > l) {

res.add(r-l == 1 ? String.valueOf(l) : String.valueOf(l) + "->" + String.valueOf(r - 1));

l = r + 1;

}

}

return res;

}

}