2025-01-25 二分查找法

src/dataANDcalc/java/algorithm/BinarySearch.java

@@ -0,0 +1,45 @@
+package algorithm;
+
+import SortAlgori.MergeSort;
+
+public class BinarySearch {
+
+    private int[] arr;
+
+    public BinarySearch(int[] arr){
+        this.arr = arr;
+    }
+
+    /**
+     * 非递归实现
+     * @param target
+     * @return
+     */
+    private int search(int target){
+        int left = 0;
+        int right = arr.length - 1;
+        while(left <= right){
+            int mid = (left + right)/2;
+            if(target == arr[mid]){
+                return mid;
+            }
+            if(target < arr[mid]){
+                right = mid - 1;
+            }
+            if(target > arr[mid]){
+                left = mid + 1;
+            }
+        }
+        return -1;
+    }
+
+    public static void main(String[] args) {
+        int[] arr = new int[]{1,3,8,10,11,67,100};
+        BinarySearch binarySearch = new BinarySearch(arr);
+        long startTime = System.currentTimeMillis();
+        int search = binarySearch.search(100);
+        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");
+    }
+}