davidvthecoder · September 9, 2013 19:28 · Sep 9, 2013
diff --git a/FindRanges.cs b/FindRanges.cs
@@ -0,0 +1,41 @@
+public List<Range> findRanges(List<int> numbers) {
+            List<Range> ranges = new List<Range>(); // create a list of ranges that will eventually be populated.
+            numbers = numbers.OrderBy(x=>x).ToList<int>(); // order the list of numbers coming in.
+            int min = numbers.Min(); // get the smallest number
+            int max = numbers.Max(); // get the largest number
+            List<int> missingNumbers = new List<int>(); // create an empty list of missing numbers
+            int i = min; // create a counter for stepping through all the numbers starting with the smallest number
+            while (i < max) { // step through each possible number from min to max.
+                if (!numbers.Contains(i)) { // if the number doesnt exist from our list, its a missing number
+                    // found a gap in the number (missing number)
+                    missingNumbers.Add(i); // add the number to the list of missing numbers.
+                }
+                i++; // increase the counter by 1.
+            }
+            int tempLow = min; // create a tempLow starting with the min since its our first low value.
+            int countInc = 1; // create a count incrementer. This is for checking for the last possible range. last found number to max.
+            foreach (int num in missingNumbers) { // step through the list of missing numbers
+                if (tempLow != num) { // if tempLow is not the same as the missing number create a new range
+                    Range r = new Range { // new rang is always the tempLow to the missing number - 1
+                        low = tempLow, // temp low which is the first valid number after the last high value
+                        high = num - 1 // last high value is the last valid number before the current missing number
+                    };
+                    // example 1,2,5,6 - 3,4 are both missing numbers. one less than missing number is a high number and the low number was the last valid high number
+                    tempLow = num + 1; // add 1 to the last misisng number in attempt to find the next lowest number- note will not be used if its a missing number with the if statement above.
+                    ranges.Add(r); // add the range to the list of ranges.
+                } else { // if tempLow is accidentally set to a missing number, increase it by 1 until is not a missing number
+                    tempLow += 1; // tempLow should be increase until it is a valid number ( not a missing number)
+                }
+                if (missingNumbers.Count == countInc) { // if this is the last item in the foreach of missing numbers ( then create the last range
+                    Range lastRange = new Range{
+                        low = tempLow, // last valid number
+                        high = max // the last and highest value
+                    };
+                    if(!ranges.Contains(lastRange)){ // if the last valid number has not been added to the ranges, do so. 
+                        ranges.Add(lastRange);
+                    }
+                }
+                    countInc += 1; // increase the foreach counter by 1.
+            }
+            return ranges; // return the list of ranges.
+        }
diff --git a/RangeClass.cs b/RangeClass.cs
@@ -0,0 +1,4 @@
+    public class Range {
+        public int low { get; set; } // low value for the range
+        public int high { get; set; } // high value for the range
+    }