DetectSubsequence.java

import java.util.Scanner;

public class DetectSubsequence{
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in); 
		int[] substring = new int[sc.nextInt()];
		int[] data = new int[sc.nextInt()];
		
		for(int i=0; i<substring.length; i++){
			substring[i] = sc.nextInt();
		}
		for(int i=0; i<data.length; i++){
			data[i] = sc.nextInt();
		}
		
		int substringIndex = 0;
		for(int i=0; i<data.length; i++){
			if(substringIndex == substring.length)
				break;
			if(data[i] == substring[substringIndex])
				substringIndex++;
		}
		
		if(substringIndex == substring.length){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}
}

PaperFold.java

import java.util.Scanner;
import static java.lang.Math.abs;

public class PaperFold {
	
	public static void main(String[] args){
		Coordinate[] coords = PaperFold.getInput(true);
		
		Line[] lines = new Line[(coords.length*(coords.length-1))/2];

		// Calculate: O(n^2)
		int i = 0;
		for(int j = 0; j < coords.length; j++){
			for(int k = j + 1; k < coords.length; k++){
				Coordinate coord1 = coords[j];
				Coordinate coord2 = coords[k];
				
				if(coord1.equals(coord2)) continue;
				float b = (coord2.y*coord2.y - coord1.y*coord1.y + coord2.x*coord2.x - coord1.x*coord1.x)/(2*(coord2.y - coord1.y));
				float m = abs(-((coord2.x - coord1.x)/(coord2.y - coord1.y)));
				if(m == Float.NEGATIVE_INFINITY || m == Float.POSITIVE_INFINITY){
					b = coord2.x - coord1.x;
				}
				lines[i] = new Line(m, b);
				i++;
			}
		}
		
		// Sort: O(n log n),
		MergeSort.sort(lines);
		
		
		// Count: O(n)
		Line prev = lines[0];
		int count = 1;
		int max = 1;
		for(int j = 1; j < lines.length; j++){
			if(lines[j].equals(prev)) count++;
			else{
				if(count>max) max = count;
				prev = lines[j];
				count = 1;
			}
		}
		if(count>max) max = count;
		
		
		
		System.out.println(max);
		
		
		
		
	}
	public static Coordinate[] getInput(boolean multiple){
		Scanner sc = new Scanner(System.in);
		Coordinate[] input;
		
		int length = Integer.parseInt(sc.nextLine().trim());
		input = new Coordinate[length];
		for(int i=0; i<input.length; i++){
			String[] line = sc.nextLine().trim().split(" ");
			input[i] = new Coordinate(Integer.parseInt(line[0]), Integer.parseInt(line[1]));
		}
		
		
		sc.close();
		return input;
	}
	
	public static class MergeSort{
		public static void sort(Line[] lines){
			sort(lines, 0, lines.length);
		}
		private static void sort(Line[] lines, int low, int high){
			int length = high - low;
			if(length <= 1)
				return;
			int middle = low + length/2;
			
			sort(lines, low, middle);
			sort(lines, middle, high);
			
			Line[] temp = new Line[length];
			int i = low, j = middle;
			for(int k = 0; k < length; k++){
				if(i == middle){
					temp[k] = lines[j++];
				}else if(j == high){
					temp[k] = lines[i++];
				}else if(lines[j].lessThan(lines[i])){
					temp[k] = lines[j++];
				}else{
					temp[k] = lines[i++];
				}
			}
			for(int k = 0; k < length; k++){
				lines[low + k] = temp[k];
			}
		}
	}
	
	public static class Coordinate{
		public final float x;
		public final float y;
		
		public Coordinate(int x, int y){
			this.x = x;
			this.y = y;
		}
		
		public Coordinate(float x, float y){
			this.x = x;
			this.y = y;
		}
		
		public boolean equals(Object o){
			if(o instanceof Coordinate){
				Coordinate coord = (Coordinate)o;
				if(coord.x == this.x && coord.y == this.y){
					return true;
				}
			}
			return false;
		}
		
		public String toString(){
			return "("+this.x+", "+this.y+")";
		}
	}
	
	public static class Line{
		public final float m;
		public final float b;
		
		public Line(float slope, float yIntercept){
			this.m = slope;
			this.b = yIntercept;
		}
		
		public boolean equals(Object o){
			if(o instanceof Line){
				Line line = (Line)o;
				if(line.b == this.b && line.m == this.m){
					return true;
				}
			}
			
			return false;
		}
		
		/**
		 * True if the CALLING OBJECT is less than or equal to the PARAMETER
		 * @param line
		 * @return
		 */
		public boolean lessThan(Line line){
			if(this.m < line.m) return true;
			if(this.m == line.m && this.b < line.b) return true;
			return false;
		}
		
		public String toString(){
			return "y = "+this.m+"x + "+this.b;
		}
	}
	
	
	
	
}