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Commit afb0888

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optimize Shell-Sort Algorithm.
1 parent 6051c87 commit afb0888

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3 files changed

+162
-5
lines changed

3 files changed

+162
-5
lines changed
Lines changed: 146 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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package com.example;
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import java.util.ArrayList;
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import java.util.Collections;
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public class LeetcodeTest {
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public static void main(String[] args) {
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// String a = "1234567891011121314151617181920";
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// String b = "2019181716151413121110987654321";
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// String a = "999999999999";
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// String b = "999999999999";
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String a = "24566";
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String b = "452053";
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// String a = "98";
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// String b = "21";
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char[] charArr1 = a.trim().toCharArray();
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char[] charArr2 = b.trim().toCharArray();
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// 字符数组转换为int[]数组
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int[] arr1 = new int[charArr1.length];
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int[] arr2 = new int[charArr2.length];
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for(int i = 0; i < charArr1.length; i++){
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arr1[i] = charArr1[i] - '0';
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}
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for(int i = 0; i < charArr2.length; i++){
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arr2[i] = charArr2[i] - '0';
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}
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// 开始计算
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// int[] result = LeetcodeTest.bigNumberMultiply2(arr1, arr2);
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// System.out.println(a + " * " + b + " = " + Arrays.toString(result).replace(", ", ""));
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System.out.println(LeetcodeTest.karatsuba(24566 , 452053));
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}
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/**
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* 大数相乘 - 模拟乘法手算累加
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*/
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public static Integer[] bigNumberMultiply(int[] arr1, int[] arr2){
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ArrayList<Integer> result = new ArrayList<>(); //中间求和的结果
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//arr2 逐位与arr1相乘
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for(int i = arr2.length - 1; i >= 0; i--){
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int carry = 0;
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ArrayList<Integer> singleList = new ArrayList<>();
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//arr2 逐位单次乘法的结果
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for(int j = arr1.length - 1; j >= 0; j--){
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int r = arr2[i] * arr1[j] + carry;
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int digit = r % 10;
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carry = r / 10;
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singleList.add(digit);
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}
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if(carry != 0){
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singleList.add(carry);
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}
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int resultCarry = 0, count = 0;
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int k = 0;
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int l = 0;
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int offset = arr2.length - 1 - i; //加法的偏移位
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ArrayList<Integer> middleResult = new ArrayList<>();
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//arr2每位乘法的结果与上一轮的求和结果相加,从右向左做加法并进位
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while (k < singleList.size() || l < result.size()) {
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int kv = 0, lv = 0;
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if (k < singleList.size() && count >= offset) {
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kv = singleList.get(k++);
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}
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if (l < result.size()) {
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lv = result.get(l++);
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}
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int sum = resultCarry + kv + lv;
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middleResult.add(sum % 10); //相加结果从右向左(高位到低位)暂时存储,最后需要逆向输出
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resultCarry = sum / 10;
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count++;
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}
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if(resultCarry != 0){
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middleResult.add(resultCarry);
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}
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result.clear();
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result = middleResult;
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}
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Collections.reverse(result); //逆向输出结果
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return result.toArray(new Integer[result.size()]);
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}
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/**
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* 大数相乘 - 模拟乘法手算累加
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*/
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public static int[] bigNumberMultiply2(int[] num1, int[] num2){
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// 分配一个空间,用来存储运算的结果,num1长的数 * num2长的数,结果不会超过num1+num2长
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int[] result = new int[num1.length + num2.length];
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// 先不考虑进位问题,根据竖式的乘法运算,num1的第i位与num2的第j位相乘,结果应该存放在结果的第i+j位上
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for (int i = 0; i < num1.length; i++){
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for (int j = 0; j < num2.length; j++){
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result[i + j + 1] += num1[i] * num2[j];
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}
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}
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//单独处理进位
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for(int k = result.length-1; k > 0; k--){
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if(result[k] > 10){
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result[k - 1] += result[k] / 10;
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result[k] %= 10;
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}
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}
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return result;
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}
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/**
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* Karatsuba乘法
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*/
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public static long karatsuba(long num1, long num2){
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if(num1 < 10 || num2 < 10) return num1 * num2;
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// 计算拆分长度
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int size1 = String.valueOf(num1).length();
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int size2 = String.valueOf(num2).length();
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int halfN = Math.max(size1, size2) / 2;
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/* 拆分为a, b, c, d */
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long a = Long.valueOf(String.valueOf(num1).substring(0, size1 - halfN));
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long b = Long.valueOf(String.valueOf(num1).substring(size1 - halfN));
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long c = Long.valueOf(String.valueOf(num2).substring(0, size2 - halfN));
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long d = Long.valueOf(String.valueOf(num2).substring(size2 - halfN));
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// 计算z2, z0, z1, 此处的乘法使用递归
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long z2 = karatsuba(a, c);
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long z0 = karatsuba(b, d);
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long z1 = karatsuba((a + b), (c + d)) - z0 - z2;
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return (long)(z2 * Math.pow(10, (2*halfN)) + z1 * Math.pow(10, halfN) + z0);
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}
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}
Lines changed: 11 additions & 0 deletions
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package com.example;
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/**
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* Created by xuewenlong on 2017年8月1日.
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*/
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public class ListNode {
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int val;
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ListNode next;
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ListNode(int x) { val = x; }
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}

‎src/main/java/com/example/SortAlgorithms.java‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -84,16 +84,16 @@ public static void insertionSort(int[] arr){
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*/
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public static void shellSort(int[] arr){
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int gap = arr.length / 2;
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System_out_println("Gap=" + gap);
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for (; gap > 0; gap /= 2) { //不断缩小gap,直到1为止
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for (int j = 0; (j+gap) < arr.length; j++){ //使用每个gap进行遍历
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for(int k = 0; (k+gap) < arr.length; k += gap){
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System_out_println("k=" + k + ", k+gap: " + (k+gap));
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System_out_println("Gap=" + gap);
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for (int j = gap; j < arr.length; j++){ //使用当前gap挨个进行遍历
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for(int k = j-gap; k >= 0; k -= gap){ //两两一组,间隔进行比较
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System_out_println("Compare: k=" + k + ", k+gap=" + (k+gap));
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if(arr[k] > arr[k+gap]){
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int temp = arr[k+gap]; //交换操作
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arr[k+gap] = arr[k];
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arr[k] = temp;
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System_out_println("Gap=" + gap + ", Sorting: " + Arrays.toString(arr));
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System_out_println(" Sorting: " + Arrays.toString(arr));
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}
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}
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}

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