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younghohyounghoh
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add CoutingInversion & Karatsuba
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‎04/CountingInverison.java

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package hw04;
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import java.io.BufferedReader;
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import java.io.FileNotFoundException;
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import java.io.FileReader;
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import java.io.IOException;
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import java.util.StringTokenizer;
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public class CountingInverison {
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private int[] arr;
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public CountingInverison(String filePath){
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String data = this.readFile(filePath);
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StringTokenizer str = new StringTokenizer(data, " ");
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arr = new int[str.countTokens()];
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for(int i = 0; str.hasMoreTokens(); i++){
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arr[i] = Integer.parseInt(str.nextToken());
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}
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}
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private int[] getArr(){
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return this.arr;
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}
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public int doSortAndCount(){
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return sortAndCount(getArr(), 0, getArr().length - 1);
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}
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private int sortAndCount(int[] arr, int start, int end){
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if(start == end){
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return 0;
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}
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int halfIndex = (start + end) / 2;
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int leftInversionCounting = sortAndCount(arr, start, halfIndex);
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int rightInversionCounting = sortAndCount(arr, halfIndex+1, end);
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int mergeInversionCounting = mergeAndCount(arr, start, halfIndex, end);
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return leftInversionCounting + rightInversionCounting + mergeInversionCounting;
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}
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private int mergeAndCount(int[] arr, int start, int mid, int end){
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int inversionCount = 0;
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int[] tempArr = new int[end - start + 1];
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int count = 0;
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int leftPointerIndex = start;
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int rightPointerIndex = mid + 1;
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int leftArrCount = mid - start + 1;
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int rightArrCount = end - (mid + 1) + 1;
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while(leftArrCount != 0 && rightArrCount != 0){
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if(arr[leftPointerIndex] > arr[rightPointerIndex]){
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tempArr[count] = arr[rightPointerIndex];
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inversionCount += leftArrCount;
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rightArrCount--;
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rightPointerIndex++;
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}else{
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tempArr[count] = arr[leftPointerIndex];
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leftArrCount--;
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leftPointerIndex++;
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}
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count++;
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}
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if(leftArrCount == 0){
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System.arraycopy(arr, rightPointerIndex, tempArr, count, rightArrCount);
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}else if(rightArrCount == 0){
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System.arraycopy(arr, leftPointerIndex, tempArr, count, leftArrCount);
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}
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System.arraycopy(tempArr, 0, getArr(), start, end - start + 1);
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return inversionCount;
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}
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private String readFile(String filePath) {
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BufferedReader br = null;
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StringTokenizer str = null;
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StringBuilder sb = null;
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String line;
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try {
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br = new BufferedReader(new FileReader(filePath));
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sb = new StringBuilder();
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while ((line = br.readLine()) != null) {
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sb.append(line);
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}
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} catch (FileNotFoundException e) {
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e.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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} finally {
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if (br != null) {
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try {
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br.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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return sb.toString();
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}
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}
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}

‎04/Karatsuba.java

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package hw04;
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import java.io.BufferedReader;
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import java.io.FileNotFoundException;
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import java.io.FileReader;
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import java.io.IOException;
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import java.math.BigInteger;
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import java.util.StringTokenizer;
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public class Karatsuba {
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private int[] arr;
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public Karatsuba(String filePath){
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String data = this.readFile(filePath);
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StringTokenizer str = new StringTokenizer(data, " |\n");
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arr = new int[str.countTokens()];
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for(int i = 0; str.hasMoreTokens(); i++){
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arr[i] = Integer.parseInt(str.nextToken());
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}
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}
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private int[] getArr(){
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return this.arr;
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}
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public BigInteger doKaratsuba(){
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return karatsuba(getArr()[0], getArr()[1]);
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}
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// private int karatsuba(int a, int b){
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// int aCount = calculateIntNumber(a);
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// int bCount = calculateIntNumber(b);
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// int maxValueCount = max(aCount, bCount);
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// if(maxValueCount == 1){
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// return a * b;
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// }
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// int exponent = maxValueCount / 2;
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// int divisor = getDivisor(exponent);
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// int x1 = a / divisor;
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// int x2 = a - (x1 * divisor);
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// int y1 = b / divisor;
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// int y2 = b - (y1 * divisor);
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// int z0 = karatsuba(x2, y2);
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// int z2 = karatsuba(x1, y1);
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// int z1 = karatsuba((x2 + x1), (y2 + y1)) - z2 - z0;
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//
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// return (z2 * divisor * divisor) + z1 * divisor + z0;
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// }
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private BigInteger karatsuba(int a, int b){
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int aCount = calculateIntNumber(a);
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int bCount = calculateIntNumber(b);
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int maxValueCount = max(aCount, bCount);
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if(maxValueCount == 1){
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return BigInteger.valueOf(a * b);
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}
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int exponent = maxValueCount / 2;
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int divisor = getDivisor(exponent);
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int x1 = a / divisor;
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int x2 = a - (x1 * divisor);
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int y1 = b / divisor;
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int y2 = b - (y1 * divisor);
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BigInteger z0 = karatsuba(x2, y2);
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BigInteger z2 = karatsuba(x1, y1);
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BigInteger z1 = karatsuba((x2 + x1), (y2 + y1)).subtract(z2).subtract(z0);
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BigInteger bigDivisor = BigInteger.valueOf(divisor);
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return z2.multiply(bigDivisor.pow(2)).add(z1.multiply(bigDivisor)).add(z0);
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}
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private int getDivisor(int exponent){
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int number = 1;
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while(exponent > 0){
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number *= 10;
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exponent--;
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}
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return number;
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}
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private int max(int a, int b){
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return (a >= b) ? a : b;
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}
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public int calculateIntNumber(int number){
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int count = 0;
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while(number > 0){
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number /= 10;
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count++;
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}
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return count;
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}
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private String readFile(String filePath) {
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BufferedReader br = null;
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StringTokenizer str = null;
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StringBuilder sb = null;
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String line;
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try {
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br = new BufferedReader(new FileReader(filePath));
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sb = new StringBuilder();
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while ((line = br.readLine()) != null) {
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sb.append(line+"\n");
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}
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} catch (FileNotFoundException e) {
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e.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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} finally {
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if (br != null) {
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try {
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br.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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return sb.toString();
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}
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}
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}

‎README.md

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# Algorithm
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*****
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1. BinaryInsertionSort / InsertionSort / MergeSort
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2. HeapSort / QuickSort
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3. Closest Pair of Points / Loop Invariant
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4. Counting Inversion / Karatsuba

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