refactor 163

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_163.java

@@ -4,54 +4,29 @@
 import java.util.List;
 
 /**
+ * 163. Missing Ranges
  * Given a sorted integer array where the range of elements are in the inclusive range [lower, upper], return its missing ranges.
- * <p>
  * For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74", "76->99"].
  */
 public class _163 {
 
     public List<String> findMissingRanges(int[] nums, int lower, int upper) {
-        List<String> res = new ArrayList<String>();
-
-        // the next number we need to find
-        long next = lower;
-        long longUpper = (long) upper;
-        if (nums.length == 0) {
-            res.add(getRange(lower, longUpper));
-            return res;
-        } else if (nums.length == 1 && nums[0] == -2147483648 && lower == -2147483648 && upper == 2147483647) {
-            res.add(getRange(lower + 1, longUpper));
-            return res;
-        }
-
-        for (int i = 0; i < nums.length; i++) {
-            // not within the range yet
-            if (nums[i] < next) continue;
-
-            // continue to find the next one
-            if (nums[i] == next) {
-                next++;
-                continue;
+        List<String> result = new ArrayList<>();
+        long low = (long) lower - 1;
+        long up = 0;
+        for (int i = 0; i <= nums.length; i++) {
+            if (i == nums.length) {
+                up = (long) upper + 1;
+            } else {
+                up = nums[i];
             }
-
-            // get the missing range string format
-            res.add(getRange(next, nums[i] - 1));
-
-            // now we need to find the next number
-            if (nums[i] < Integer.MAX_VALUE) next = nums[i] + 1;
-            else break;
+            if (up == low + 2) {
+                result.add(low + 1 + "");
+            } else if (up > low + 2) {
+                result.add((low + 1) + "->" + (up - 1));
+            }
+            low = up;
         }
-
-        // do a final check
-        if (next > Integer.MIN_VALUE && next <= longUpper && longUpper < Integer.MAX_VALUE)
-            res.add(getRange(next, longUpper));
-        if (next == Integer.MIN_VALUE && longUpper == Integer.MAX_VALUE && nums.length == 0)
-            res.add(getRange(next, longUpper));
-
-        return res;
-    }
-
-    String getRange(long n1, long n2) {
-        return (n1 == n2) ? String.valueOf(n1) : String.format("%d->%d", n1, n2);
+        return result;
     }
 }