局部最小值的位置对数器,联系

src/leo/class01/BSAwesome.java

@@ -1,5 +1,9 @@
 package leo.class01;
 
+import com.sun.org.apache.xpath.internal.functions.FuncFalse;
+import leo.util.ArrayUtil;
+import sun.security.util.Length;
+
 /**
  * @author Leo
  * @ClassName BSAwesome
@@ -36,4 +40,116 @@ public class BSAwesome {
 
 
     }
+
+
+    public static int BSAwesome1(int[] arr) {
+        if (arr.length == 0 || arr == null) {
+            return -1;
+        }
+        if (arr.length == 1||arr[0] < arr[1]) {
+            return 0;
+        }
+        if (arr[arr.length-1]<arr[arr.length-2]){
+            return arr.length - 1;
+        }
+        int L = 1;
+        int R = arr.length - 2;
+        int mid = 0;
+        while (L < R) {
+            mid = L + ((R - L) >> 1);
+            if (arr[mid] > arr[mid - 1]) {
+                R = mid - 1;
+            } else if (arr[mid] > arr[mid + 1]) {
+                L = mid + 1;
+            }else {
+                return mid;
+            }
+        }
+        return -1;
+    }
+
+    public static int testBSAwesome(int[] arr) {
+        if (arr.length == 0 || arr == null) {
+            return -1;
+        }
+        if (arr.length >= 1&&arr[0] < arr[1]) {
+            return 0;
+        }
+        if (arr[arr.length - 1] < arr[arr.length - 2]) {
+            return arr.length - 1;
+        }
+        Integer first = null;
+
+        Integer end = null;
+
+        for (int i = 1; i < arr.length-2; i++) {
+            int res = arr[i];
+            if (first == null) {
+                first = i-1;
+            }
+            if (end == null) {
+                end = i + 1;
+            }
+            if (arr[first] > res && res < arr[end]) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+
+
+
+
+    public static int verifyBSAwesome(int[] arr, int index) {
+        if (arr.length == 0 || index == -1) {
+            return -1;
+        }
+        if (arr.length == 1 && index == 0) {
+            return index;
+        }
+        if (arr.length >= 1 && index == 0 ){
+            if (index + 1< arr.length && arr[index] < arr[index + 1]) {
+                return index;
+            }
+        }
+        if (index - 1 >= 0) {
+            if (index == arr.length-1  ) {
+                if (arr[index] < arr[index - 1]) {
+                    return index;
+                }
+            }
+            if (index == arr.length - 1) {
+                if (arr[arr.length - 1] < arr[arr.length - 2]) {
+                    return index;
+                }
+            }
+            if (arr[index - 1] > arr[index] && arr[index] < arr[index + 1]) {
+                return index;
+            }
+        }
+        return -1;
+    }
+
+    public static void main(String[] arg) {
+        int maxSize = 80;
+        int range = 80;
+        int testTime  = 100000;
+        boolean succeed = true;
+        for (int i = 0; i < testTime; i++) {
+            int[] arr = ArrayUtil.randomAdjacentNotEqualArray(maxSize, range);
+            final int index = BSAwesome1(arr);
+            final int verifyIndex = verifyBSAwesome(arr,index);
+            if (index != verifyIndex) {
+                succeed = false;
+                ArrayUtil.printArr(arr, "index : " + index + " | testIndex : " + verifyIndex);
+                break;
+            }
+        }
+        System.out.println(succeed ? "Nice!" : "Fucking Fucked!");
+    }
+
+
+
+
 }

src/leo/util/ArrayUtil.java

@@ -1,5 +1,7 @@
 package leo.util;
 
+import org.omg.CORBA.IRObject;
+
 import java.util.Arrays;
 
 /**
@@ -130,14 +132,14 @@ public class ArrayUtil {
         arrName = arrName == null ? "arr" : arrName;
         arrStr.append(" " + arrName + " = [");
         if (arr == null || arr.length <= 0) {
-            System.out.println();
             arrStr.append("]");
+            System.out.println(arrStr);
+            return;
         }
 
         for (int i = 0; i < arr.length; i++) {
-            arrStr.append(" " + arr[i] + ",");
+            arrStr.append(" " + arr[i] + (i==arr.length-1?"":","));
         }
-        arrStr.substring(0, arrStr.length() - 2);
         arrStr.append(" ]");
         System.out.println(arrStr);
     }
@@ -154,6 +156,31 @@ public class ArrayUtil {
 
     }
 
+    /**
+     * 功能描述 : 随机生成无序数组且任意相邻的数不相等
+     * @author Leo
+     * @date 2020/11/13 11:21 上午
+     * @param maxSize
+     * @param range
+     * @return int[]
+     */
+    public static int[] randomAdjacentNotEqualArray(int maxSize, int range) {
+        int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
+        Integer preNum = null;
+        for (int i = 0; i < arr.length; i++) {
+            int randomNum = (int) ((range + 1) * Math.random() - range  * Math.random());
+
+            if (preNum != null) {
+                while (preNum == randomNum) {
+                    randomNum = (int) ((range + 1) * Math.random() - range  * Math.random());
+                }
+            }
+            preNum = randomNum;
+            arr[i] = randomNum;
+        }
+        return arr;
+    }
+
 
 
 }