Runtime analysis done in lecture

src/main/java/h21/Products.java

+package h21;
+
+import java.util.Arrays;
+import java.util.HashMap;
+
+public class Products {
+
+	public static int countProducts(int[] a) {
+		int total = 0;
+		
+		for(int i=0; i<a.length; i++) {
+			for(int j=i; j<a.length; j++) {
+				int prod = a[i]*a[j];
+				for(int k=0; k<a.length; k++) {
+					if(a[k]==prod)
+						total++;
+				}
+			}
+		}
+		
+		return total;
+	}
+
+	//TODO: improve this
+	public static int countProducts2(int[] a) {
+		int total = 0;
+		
+		for(int i=0; i<a.length; i++) {
+			for(int j=i; j<a.length; j++) {
+				int prod = a[i]*a[j];
+				for(int k=0; k<a.length; k++) {
+					if(a[k]==prod)
+						total++;
+				}
+			}
+		}
+		
+		return total;
+	}
+}

src/main/java/h21/RuntimeAnalysis.java

+package h21;
+
+
+public class RuntimeAnalysis {
+
+	public static int numPairs(int n) {
+		int count = 0;	//1*O(1)
+		for(int i=0; i<n; i++) { //n iterasjoner
+			for(int j=i+1; j<n; j++) { //O(n) iterasjoner
+				count++;	//O(n^2) * O(1)
+			}
+		}
+		return count;
+	}
+			
+	public static void printProducts(int n) {
+		int a=0; //O(1)
+		int b=n; //O(1)
+
+		while(a<=b) { //O(n) iterasjoner
+			if(a*b==n) {
+				System.out.println(a+"*"+b+"="+a*b);  //O(1)
+				a++; //O(1)
+				b--; //O(1)
+			}
+			else if(a*b>n)
+				b--; //O(1)
+			else if(a*b<n)
+				a++; //O(1)
+		}
+	}
+
+
+	public static void printProducts2(int n) {
+		int a=1; //O(1)
+		int b=n; //O(1)
+
+		while(a<=b) { //O(sqrt(n))
+			if(a*b==n) {
+				System.out.println(a+"*"+b+"="+a*b); //O(1)
+				a++; //O(1)
+				b--; //O(1)
+			}
+			else {
+				if(a*b>n)
+					b=n/a; //O(1)
+				else if(a*b<n)
+					a++; //O(1)
+			}
+		}
+	}
+	
+	public static String loopDeLoop(int n) {
+		String lyrics = "";  //O(1)
+		for(int i=0; i<n; i++) { //n iterasjoner
+			lyrics += "Loop de loop, flip flop.\n"; //O(lyrics.length)= O(n)
+			lyrics += "Flying in an aeroplane.\n"; 
+		}
+		return lyrics;
+	}
+	
+}