2025-01-18 二分查找法

src/dataANDcalc/java/Search/BinarySearch.java

@@ -0,0 +1,47 @@
+package Search;
+
+import SortAlgori.MergeSort;
+
+public class BinarySearch {
+
+    private int[] arr;
+
+    public BinarySearch(int[] arr){
+        this.arr = arr;
+    }
+
+    private int search(int left, int right, int value){
+        int index = -1;
+        if(left >= right){
+            if(arr[left] == value){
+                return left;
+            }
+            return index;
+        }
+        int mid = (left + right)/2;
+        if(value == arr[mid]){
+            return mid;
+        }
+        if(value > arr[mid]){
+            index = search(mid + 1, right, value);
+        }
+        if(value < arr[mid]){
+            index = search(left, mid - 1, value);
+        }
+        return index;
+    }
+
+    public static void main(String[] args) {
+        int[] arr = new int[]{1,9,11,-1,34,89,23,53,124,52};
+        MergeSort mergeSort = new MergeSort(arr);
+        mergeSort.mergeSort(0, arr.length-1);
+        System.out.println("排序后的序列：");
+        mergeSort.show();
+        BinarySearch binarySearch = new BinarySearch(mergeSort.getArr());
+        long startTime = System.currentTimeMillis();
+        int search = binarySearch.search(0, arr.length-1, 124);
+        long endTime = System.currentTimeMillis();
+        System.out.println("查找到的下标是：" + search);
+        System.out.println("查找所花费的时间：" + (endTime - startTime) + "ms");
+    }
+}

src/dataANDcalc/java/SortAlgori/MergeSort.java

@@ -6,6 +6,14 @@ public class MergeSort {
 
     private int[] temp;
 
+    public int[] getArr() {
+        return arr;
+    }
+
+    public void setArr(int[] arr) {
+        this.arr = arr;
+    }
+
     public MergeSort(int[] arr){
         this.arr = arr;
 //        this.arr = new int[]{8,4,5,7,1,3,6,2};