From e33ea7ecde89cd0b697ef9f6e8564bd5e3cb4288 Mon Sep 17 00:00:00 2001 From: SeonJae Date: Mon, 13 Nov 2017 12:39:56 +0900 Subject: [PATCH] ClosestPair --- ClosestPair/ClosestPair.java | 211 +++++++++++++++++++++++++++++++++++ ClosestPair/closest_data.txt | 12 ++ 2 files changed, 223 insertions(+) create mode 100644 ClosestPair/ClosestPair.java create mode 100644 ClosestPair/closest_data.txt diff --git a/ClosestPair/ClosestPair.java b/ClosestPair/ClosestPair.java new file mode 100644 index 00000000..760ef7fd --- /dev/null +++ b/ClosestPair/ClosestPair.java @@ -0,0 +1,211 @@ +import java.io.*; +import java.util.*; + +public class ClosestPair { + static int count = 0;// array length + static int secondCount = 0;// array length + static Location array[] = new Location[10000]; + static Location point1 = null; // Minimum point coordinate + static Location point2 = null; // Minimum point coordinate + static double minNum = Double.MAX_VALUE;// Minimum point length + + private static class Location { // Location class + double x = 0, y = 0; + + public Location(double x, double y) { //Save x, y coordinates + this.x = x; + this.y = y; + } + } + + public static int xPartition(Location[] a, int first, int last) { // x-axis Quick Sorting + Location pivot = a[last]; // pivot + int pIndex = last; + int i = first - 1; + Location temp; // Temporarily store the value for position transformation + for (int j = first; j <= last - 1; j++) { + if (a[j].x <= pivot.x) { // Less than or less than pivot + i++; + temp = a[i]; // array[i] <-> array[j] + a[i] = a[j]; + a[j] = temp; + } + } + i++; + temp = a[i];// array[pivot] <-> array[i] + a[i] = a[pIndex]; + a[pIndex] = temp; + return i;// pivot index + } + public static int yPartition(Location[] a, int first, int last) { //y-axis Quick Sorting + Location pivot = a[last]; // pivot + int pIndex = last; + int i = first - 1; + Location temp; // Temporarily store the value for position transformation + for (int j = first; j <= last - 1; j++) { + if (a[j].y <= pivot.y) { // Less than or less than pivot + i++; + temp = a[i]; // array[i] <-> array[j] + a[i] = a[j]; + a[j] = temp; + } + } + i++; + temp = a[i];// array[pivot] <-> array[i] + a[i] = a[pIndex]; + a[pIndex] = temp; + return i;// pivot index + } + + public static void xQuickSort(Location[] a, int first, int last) { //x-axis Quick Sorting + if (first < last) { + int q = xPartition(a, first, last); // pivot + xQuickSort(a, first, q - 1); // Left + xQuickSort(a, q + 1, last); // Right + } + } + + public static void yQuickSort(Location[] a, int first, int last) { //y-axis Quick Sorting + if (first < last) { + int q = yPartition(a, first, last); // pivot + yQuickSort(a, first, q - 1); // Left + yQuickSort(a, q + 1, last); // Right + } + } + + public static double closestPair(Location[] a, int indexNum, int first, int last) {// closestPair + Location divideArray[] = new Location[indexNum]; // array stored before divide + System.arraycopy(a, 0, divideArray, 0, indexNum); // Copy from previous array + + int totalNum = indexNum; // number of coordinates in the divideArray array + int divideX = indexNum / 2; // Intermediate value for divide + Location leftArray[] = new Location[divideX]; //divide - left array + Location rightArray[] = new Location[totalNum - divideX]; //divide - right array + + if (indexNum <= 3) { // If the number of coordinates is 3 or less + return bruteForce(divideArray); + } + System.arraycopy(divideArray, 0, leftArray, 0, divideX); //divide - left array + System.arraycopy(divideArray, divideX, rightArray, 0, totalNum - divideX); //divide - right array + + double minLeftArea = 0; //Minimum length of left array + double minRightArea = 0; //Minimum length of right array + double minValue = 0; //Minimum lengt + + minLeftArea = closestPair(leftArray, divideX, 0, divideX - 1); // recursive closestPair + minRightArea = closestPair(rightArray, totalNum - divideX, divideX, totalNum - divideX - 1); + minValue = Math.min(minLeftArea, minRightArea);// window size (= minimum length) + + // Create window + for (int i = 0; i < totalNum; i++) { // Set the size for creating a window and creating a new array for the coordinates in the window + double xGap = Math.abs(divideArray[divideX].x - divideArray[i].x); + if (xGap < minValue) { + secondCount++; // size of the array + } else { + if (divideArray[i].x > divideArray[divideX].x) { + break; + } + } + } + Location firstWindow[] = new Location[secondCount]; // new array for coordinates in window + int k = 0; + for (int i = 0; i < totalNum; i++) { + double xGap = Math.abs(divideArray[divideX].x - divideArray[i].x); + if (xGap < minValue) { // if it's inside a window + firstWindow[k] = divideArray[i]; // put in an array + k++; + } else { + if (divideArray[i].x > divideArray[divideX].x) { + break; + } + } + } + yQuickSort(firstWindow, 0, secondCount - 1);// Sort by y coordinates + / * Coordinates in Window * / + double length = 0; + for (int i = 0; i < secondCount - 1; i++) { // size comparison within window + for (int j = (i + 1); j < secondCount; j++) { + double xGap = Math.abs(firstWindow[i].x - firstWindow[j].x); + double yGap = Math.abs(firstWindow[i].y - firstWindow[j].y); + if (yGap < minValue) { + length = (double) Math.sqrt(Math.pow(xGap, 2) + Math.pow(yGap, 2)); + if (length < minValue) { // If the measured distance is less than the current minimum distance + minValue = length;// Change minimum distance to current distance + if (length < minNum) { // Conditional statement for registering final coordinate + minNum = length; + point1 = firstWindow[i]; + point2 = firstWindow[j]; + } + } + } + else + break; + } + } + secondCount = 0; + return minValue; + } + + public static double bruteForce(Location[] array) { // When the number of coordinates is less than 3 + double minValue = Double.MAX_VALUE; // minimum distance + double length = 0; + double xGap = 0, yGap = 0; // Difference between x, y coordinates + if (array.length == 2) { // When there are two coordinates + xGap = (array[0].x - array[1].x); // Difference between x coordinates + yGap = (array[0].y - array[1].y); // Difference between y coordinates + length = (double) Math.sqrt(Math.pow(xGap, 2) + Math.pow(yGap, 2)); // distance between coordinates + if (length < minNum) { // Conditional statement for registering final coordinate + minNum = length; + point1 = array[0]; + point2 = array[1]; + } + return length; + } else if (array.length == 3) { // When there are 3 coordinates + for (int i = 0; i < array.length - 1; i++) { + for (int j = (i + 1); j < array.length; j++) { + xGap = (array[i].x - array[j].x); // Difference between x coordinates + yGap = (array[i].y - array[j].y); // Difference between y coordinates + length = (double) Math.sqrt(Math.pow(xGap, 2) + Math.pow(yGap, 2)); // distance between coordinates + if (length < minValue) { // If the measured distance is less than the current minimum distance + minValue = length; // Change minimum distance to current distance + if (length < minNum) { // Conditional statement for registering final coordinate + minNum = length; + point1 = array[i]; + point2 = array[j]; + } + } + } + } + return minValue; + } + return minValue; + } + + public static void main(String[] args) throws IOException { + // TODO Auto-generated method stub + StringTokenizer token; + + BufferedReader in = new BufferedReader(new FileReader("closest_data.txt")); + //Input data consists of one x-coordinate and one y-coordinate + String ch; + + System.out.println("Input data"); + while ((ch = in.readLine()) != null) { + token = new StringTokenizer(ch, " "); + + array[count] = new Location(Double.parseDouble(token.nextToken()), Double.parseDouble(token.nextToken())); // put in an array + count++; // the number of coordinates actually in the array + System.out.println("x: "+array[count - 1].x + ", y: " + array[count - 1].y); + } + + xQuickSort(array, 0, count - 1); // Sorting by x value + + double result; // minimum distance + result = closestPair(array, count, 0, count - 1); // ClosestPair start + System.out.println("Output Data");// minimum distance coordinates and distance output + System.out.println("(" + point1.x + ", " + point1.y + ")"); + System.out.println("(" + point2.x + ", " + point2.y + ")"); + System.out.println("Minimum Distance : " + result); + + } +} diff --git a/ClosestPair/closest_data.txt b/ClosestPair/closest_data.txt new file mode 100644 index 00000000..8ebef63f --- /dev/null +++ b/ClosestPair/closest_data.txt @@ -0,0 +1,12 @@ +2 3 +2 16 +3 9 +6 3 +7 7 +9 12 +10 11 +15 2 +15 19 +16 11 +17 13 +19 4