adding SelectionSort class for algorithm complexity notes.

algorithm_complexity/Makefile

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+default:
+	javac SelectionSort.java
+	java SelectionSort

algorithm_complexity/SelectionSort.java

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+import java.util.Arrays;
+
+public class SelectionSort {
+
+	public static void selection_sort(char[] s) {
+		int min; // indexes of minimum
+		int n = s.length;
+		for(int i=0; i<n; i++) {
+
+			// Print the String at each step:
+			System.out.println(new String(s));
+
+			min = i;
+			for(int j=i+1; j<n; j++) { 
+				if(s[j] < s[min]) {
+					min = j;
+				}
+			}
+			swap(s, i, min);
+		}
+	}
+
+	public static void swap(char[] s, int i, int min) {
+		char temp = s[i];
+		s[i] = s[min];
+		s[min] = temp;
+	}
+
+	public static void main(String[] args) { 
+		char[] s = "SELECTIONSORT".toCharArray();
+		System.out.println(Arrays.toString(s));
+		selection_sort(s);
+		System.out.println(Arrays.toString(s));
+	}
+}