add binary search

Author: AaronLinRC

src/main/kotlin/newcode/LocalMinimum.kt

@@ -0,0 +1,30 @@
+package newcode
+
+import org.junit.Test
+
+class LocalMinimum {
+    fun min(array: IntArray): Int {
+        if (array.isEmpty() || array.size < 2) return 0
+        if (array[0] < array[1]) return 0
+        if (array.last() < array[array.lastIndex - 1]) return array.lastIndex
+        var pL = 0
+        var pR = array.lastIndex
+        while (pL < pR) {
+            val mid = (pL + pR) / 2
+            if (array[mid] > array[mid - 1]) {
+                pR = mid
+            } else if (array[mid] > array[mid + 1]) {
+                pL = mid + 1
+            } else {
+                return mid
+            }
+        }
+        return 0
+    }
+
+    @Test
+    fun test() {
+        val array = intArrayOf(5535435, 45345, 5431, 64, 7, 6, 5, 52)
+        println(this.min(array))
+    }
+}

src/main/kotlin/search/BinarySearch.kt

@@ -0,0 +1,21 @@
+package search
+
+object BinarySearch {
+    fun search(array: IntArray, target: Int): Boolean {
+        if (array.isEmpty()) return false
+        var pL = 0
+        var pR = array.lastIndex
+
+        while (pL < pR) {
+            val mid = (pL + pR) / 2
+            if (target < array[mid]) {
+                pR = mid
+            } else if (target > array[mid]) {
+                pL = mid + 1
+            } else {
+                return true
+            }
+        }
+        return false
+    }
+}

src/main/kotlin/search/TestSearch.kt

@@ -0,0 +1,14 @@
+package search
+
+import org.junit.Assert
+import org.junit.Test
+
+class TestSearch {
+    private val array = intArrayOf(2, 2, 6, 6, 34, 34, 45, 45, 754, 3462)
+
+    @Test
+    fun testBinary(){
+        Assert.assertTrue(BinarySearch.search(array,6))
+        Assert.assertFalse(BinarySearch.search(array,72))
+    }
+}