added inf2440 hw3

inf2440/hw3/MultiRadix.java

@@ -0,0 +1,107 @@
+import java.util.*;
+/***********************************************************
+ * Oblig 3 - sekvensiell kode, INF2440 v2017.
+ *            Ifi, Uio, Arne Maus
+ * for store verdier av n > 100 m, kjør (f.eks):
+ *     >java -Xmx16000m MultiRadix 1000000000
+ ************************************************************/
+class MultiRadix{
+	int n;
+	int [] a;
+	final static int NUM_BIT = 7; // alle tall 6-11 .. finn ut hvilken verdi som er best
+
+	public static void main(String [] args) {
+		if (args.length != 1) {
+			System.out.println(" bruk : >java SekvensiellRadix <n> ");
+		} else {
+			int n = Integer.parseInt(args[0]);
+			new MultiRadix().doIt(n);
+		}
+	} // end main
+
+	void doIt (int len) {
+		a = new int[len];
+		Random r = new Random(123);
+		for (int i =0; i < len;i++) {
+			a[i] = r.nextInt(len);
+		}
+		a = radixMulti(a);
+	} // end doIt
+
+	int []  radixMulti(int [] a) {
+		long tt = System.nanoTime();
+		// 1-5 digit radixSort of : a[]
+		int max = a[0], numBit = 2, numDigits, n =a.length;
+		int [] bit ;
+
+		// a) finn max verdi i a[]
+		for (int i = 1 ; i < n ; i++)
+			if (a[i] > max) max = a[i];
+		while (max >= (1L<<numBit) )numBit++; // antall binaere siffer i max
+
+		// bestem antall bit i numBits sifre
+		numDigits = Math.max(1, numBit/NUM_BIT);
+		bit = new int[numDigits];
+		int rest = (numBit%numDigits), sum =0;;
+
+		// fordel bitene vi skal sortere paa jevnt
+		for (int i = 0; i < bit.length; i++){
+			bit[i] = numBit/numDigits;
+			if ( rest-- > 0)  bit[i]++;
+		}
+
+		int[] t=a, b = new int [n];
+
+		for (int i =0; i < bit.length; i++) {
+			radixSort( a,b,bit[i],sum );    // i-te siffer fra a[] til b[]
+			sum += bit[i];
+			// swap arrays (pointers only)
+			t = a;
+			a = b;
+			b = t;
+		}
+		if (bit.length%2 != 0 ) {
+			// et odde antall sifre, kopier innhold tilbake til original a[] (nå b)
+			System.arraycopy (a,0,b,0,a.length);
+		}
+
+		double tid = (System.nanoTime() -tt)/1000000.0;
+		System.out.println("\nSorterte "+n+" tall paa:" + tid + "millisek.");
+		testSort(a);
+		return a;
+	} // end radixMulti
+
+	/** Sort a[] on one digit ; number of bits = maskLen, shiftet up 'shift' bits */
+	void radixSort ( int [] a, int [] b, int maskLen, int shift){
+		System.out.println(" radixSort maskLen:"+maskLen+", shift :"+shift);
+		int  acumVal = 0, j, n = a.length;
+		int mask = (1<<maskLen) -1;
+		int [] count = new int [mask+1];
+
+		// b) count=the frequency of each radix value in a
+		for (int i = 0; i < n; i++) {
+			count[(a[i]>>> shift) & mask]++;
+		}
+
+		// c) Add up in 'count' - accumulated values
+		for (int i = 0; i <= mask; i++) {
+			j = count[i];
+			count[i] = acumVal;
+			acumVal += j;
+		}
+		// d) move numbers in sorted order a to b
+		for (int i = 0; i < n; i++) {
+			b[count[(a[i]>>>shift) & mask]++] = a[i];
+		}
+
+	}// end radixSort
+
+	void testSort(int [] a){
+		for (int i = 0; i< a.length-1;i++) {
+			if (a[i] > a[i+1]){
+				System.out.println("SorteringsFEIL på plass: "+i +" a["+i+"]:"+a[i]+" > a["+(i+1)+"]:"+a[i+1]);
+				return;
+			}
+		}
+	}// end simple sorteingstest
+}// end SekvensiellRadix