add a solution for 34

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_34.java

@@ -85,4 +85,52 @@ public int[] searchRange(int[] nums, int target) {
             return result;
         }
     }
+
+    public static class Solution3 {
+        /**
+         * My completely original solution on 1/15/2022. A great practice to solidify binary search basics.
+         */
+        public int[] searchRange(int[] nums, int target) {
+            int left = 0;
+            int right = nums.length - 1;
+            int[] ans = new int[]{-1, -1};
+            while (left < right) {
+                int mid = left + (right - left) / 2;
+                if (nums[mid] > target) {
+                    right = mid - 1;
+                } else if (nums[mid] < target) {
+                    left = mid + 1;
+                } else {
+                    right = mid - 1;
+                    ans[0] = mid;
+                    ans[1] = mid;
+                }
+            }
+            if (left < nums.length && nums[left] != target && right > 0 && nums[right] != target && right + 1 < nums.length && nums[right + 1] != target) {
+                return ans;
+            }
+            if (left < nums.length && nums[left] == target) {
+                ans[0] = left;
+                ans[1] = left;
+            }
+            right = nums.length - 1;
+            while (left < right) {
+                int mid = left + (right - left) / 2;
+                if (nums[mid] < target) {
+                    left = mid + 1;
+                } else if (nums[mid] > target) {
+                    right = mid - 1;
+                } else {
+                    ans[1] = mid;
+                    left = mid + 1;
+                }
+            }
+            if (right >= 0 && nums[right] == target) {
+                ans[1] = right;
+            } else if (left < nums.length && nums[left] == target) {
+                ans[1] = left;
+            }
+            return ans;
+        }
+    }
 }

src/test/java/com/fishercoder/_34Test.java

@@ -9,25 +9,29 @@
 public class _34Test {
     private static _34.Solution1 solution1;
     private static _34.Solution2 solution2;
+    private static _34.Solution3 solution3;
     private static int[] nums;
 
     @BeforeClass
     public static void setup() {
         solution1 = new _34.Solution1();
         solution2 = new _34.Solution2();
+        solution3 = new _34.Solution3();
     }
 
     @Test
     public void test1() {
         nums = new int[]{1, 2, 3};
         assertArrayEquals(new int[]{1, 1}, solution1.searchRange(nums, 2));
         assertArrayEquals(new int[]{1, 1}, solution2.searchRange(nums, 2));
+        assertArrayEquals(new int[]{1, 1}, solution3.searchRange(nums, 2));
     }
 
     @Test
     public void test2() {
         nums = new int[]{};
         assertArrayEquals(new int[]{-1, -1}, solution1.searchRange(nums, 0));
         assertArrayEquals(new int[]{-1, -1}, solution2.searchRange(nums, 0));
+        assertArrayEquals(new int[]{-1, -1}, solution3.searchRange(nums, 0));
     }
 }