Merge pull request #201 from AlgoLeadMe/8-mjj111

8-mjj111

mjj111/SearchForARange.java

@@ -0,0 +1,44 @@
+class SearchForARange {
+    public int[] searchRange(int[] nums, int target) {
+        int firstOccurrence = this.findBound(nums, target, true);
+
+        if (firstOccurrence == -1) {
+            return new int[] { -1, -1 };
+        }
+
+        int lastOccurrence = this.findBound(nums, target, false);
+
+        return new int[] { firstOccurrence, lastOccurrence };
+    }
+
+    private int findBound(int[] nums, int target, boolean isFirst) {
+        int N = nums.length;
+        int begin = 0, end = N - 1;
+
+        while (begin <= end) {
+            int mid = (begin + end) / 2;
+
+            if (nums[mid] == target) {
+                if (isFirst) {
+                    if (mid == begin || nums[mid - 1] != target) {
+                        return mid;
+                    }
+
+                    end = mid - 1;
+                } else {
+                    if (mid == end || nums[mid + 1] != target) {
+                        return mid;
+                    }
+
+                    begin = mid + 1;
+                }
+            } else if (nums[mid] > target) {
+                end = mid - 1;
+            } else {
+                begin = mid + 1;
+            }
+        }
+
+        return -1;
+    }
+}