Add 163_Missing_Ranges.java

Author: Sean Prashad

Strings/163_Missing_Ranges.java

@@ -0,0 +1,32 @@
+class Solution {
+    public List<String> findMissingRanges(int[] nums, int lower, int upper) {
+        List<String> result = new ArrayList<>();
+
+        if (nums.length == 0) {
+            result.add(intervalToString(lower, upper));
+            return result;
+        }
+
+        if (lower < nums[0]) {
+            result.add(intervalToString(lower, nums[0] - 1));
+        }
+
+        for (int i = 0; i < nums.length - 1; i++) {
+            if (nums[i] == nums[i + 1] || nums[i] + 1 == nums[i + 1]) {
+                continue;
+            }
+
+            result.add(intervalToString(nums[i] + 1, nums[i + 1] - 1));
+        }
+
+        if (nums[nums.length - 1] < upper) {
+            result.add(intervalToString(nums[nums.length - 1] + 1, upper));
+        }
+
+        return result;
+    }
+
+    private String intervalToString(int low, int high) {
+        return low == high ? low + "" : low + "->" + high;
+    }
+}