2025-01-15 1.时间复杂度 2.冒泡排序

src/dataANDcalc/java/SortAlgori/BubbleSort.java

@@ -0,0 +1,67 @@
+package SortAlgori;
+
+import java.util.Scanner;
+
+public class BubbleSort {
+
+    private int[] arr;
+
+    public BubbleSort(String str){
+        String[] splitArrs = str.split(";");
+        arr = new int[splitArrs.length];
+        for (int i = 0; i < splitArrs.length; i++) {
+            arr[i] = Integer.parseInt(splitArrs[i]);
+        }
+    }
+
+    public BubbleSort(int[] arr){
+        this.arr = arr;
+    }
+
+
+    /**
+     * 可以进行一个优化，如果在某一趟排序中没发生过交换，就说明已经排好序了
+     */
+    public void sort(){
+        boolean flag = false;
+        for (int i=0 ; i<arr.length-1; i++){
+            for(int j=0; j<arr.length-i-1; j++){
+                if(arr[j]>arr[j+1]){
+                    flag = true;
+                    int temp = arr[j+1];
+                    arr[j+1] = arr[j];
+                    arr[j] = temp;
+                }
+            }
+            if(!flag){
+                break;
+            }else {
+                flag = false;
+            }
+        }
+    }
+
+    public void show(){
+        for (int i = 0; i < arr.length; i++) {
+            System.out.print(arr[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static void main(String[] args) {
+        int[] arr = new int[10000];
+        System.out.println("排序前的序列：");
+        for(int i=0; i<10000; i++){
+            arr[i] = (int)(Math.random()*1000000);
+            System.out.print(arr[i] + " ");
+        }
+        System.out.println();
+        BubbleSort bubbleSort = new BubbleSort(arr);
+        long startTime = System.currentTimeMillis();
+        bubbleSort.sort();
+        long endTime = System.currentTimeMillis();
+        System.out.println("排序后的序列：");
+        bubbleSort.show();
+        System.out.println("排序所花费的时间：" + (endTime - startTime) + "ms");
+    }
+}

src/dataANDcalc/java/SortAlgori/TimeComplex.java

@@ -0,0 +1,40 @@
+package SortAlgori;
+
+public class TimeComplex {
+
+    private int constant(int n){
+        return (1+n)*n/2;
+    }
+
+    private int log2n(int n){
+        int i = 1;
+        while (i < n){
+            i = i * 2;
+        }
+        return i;
+    }
+
+    private void linear(int n){
+        for(int i = 0; i<n; i++){
+            System.out.printf("i = %d\n",i);
+        }
+    }
+
+    private void nlog2n(int n){
+        for(int i = 0; i<n; i++){
+            int j = 1;
+            while (j < n){
+                j = j * 2;
+            }
+            System.out.printf("i = %d\n",i);
+        }
+    }
+
+    private void square(int n){
+        for(int i = 0; i<n; i++){
+            for(int j = 0; j<n; j++){
+                System.out.printf("i = %d,j = %d\n",i,j);
+            }
+        }
+    }
+}