Add Day 10 & Day 11 - Java Implementation (#116)

* Update @chaitanya-bhojwani as a contributor

* Java Implementation

* Add day 10 and day 11

Author: chaitanya-bhojwani

day10/Java/permutations.java

@@ -0,0 +1,55 @@
+/**
+        * @author: chaitanya-bhojwani
+        * @date: 01-01-2019
+ **/
+import java.util.*;
+class permutations{
+	public static void main(String args[]){
+		System.out.println("---------Daily Codes - Day 10 ---------------");
+		System.out.println("---String Permutation Problem---");
+		System.out.println("Enter the string for permutations: ");
+		Scanner sc = new Scanner(System.in);
+		String input = sc.next();
+		char[] in = input.toCharArray();
+		System.out.println("Possible permutations of String are: ");
+		generator("",in);
+	}
+	static void generator(String prev, char[] in){
+		char[] out = new char[in.length];
+		for(int i=0;i<in.length;i++){
+			out[0] = in[i];
+			int k=1;
+			for(int j=0;j<in.length;j++){
+				if(out[0]!=in[j]){
+					out[k] = in[j];
+					k++;
+				}
+			}
+			if(out.length>3){
+				generator(prev+String.valueOf(out[0]),Arrays.copyOfRange(out, 1, out.length));
+			}
+			else{
+				print_permutation(prev,out);
+			}
+		}
+	}
+	static void print_permutation(String prev, char[] permute){
+		System.out.println(prev+""+String.valueOf(permute));
+		char[] previous = new char[permute.length];
+		System.arraycopy(permute,0,previous,0,permute.length);
+		for(int p=0;p<permute.length-2;p++){
+			char[] next = new char[previous.length];
+			next[0] = permute[0];
+			for(int q=1;q<permute.length;q++){
+				if(q==1){
+					next[q] = previous[previous.length-1];
+				}
+				else{
+					next[q] = previous[q-1];
+				}
+			}
+			System.out.println(prev+""+String.valueOf(next));
+			System.arraycopy(next,0,previous,0,next.length);
+		}
+	}
+}

day11/Java/longest_common_substring.java

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+/**
+        * @author: chaitanya-bhojwani
+        * @date: 03-01-2019
+ **/
+import java.util.*;
+class longest_common_substring{
+	public static void main(String args[]){
+		System.out.println("---------Daily Codes - Day 11 ---------------");
+		System.out.println("---Longest Common Substring Problem---");
+		System.out.println("Enter the first string: ");
+		Scanner sc = new Scanner(System.in);
+		String first = sc.next();
+		System.out.println("Enter the second string: ");
+		String second = sc.next();
+		int maxval = 0;
+		int maxposi = 0;
+		int maxposj = 0;
+		String result = "";
+		int[][] mat = new int[first.length()][second.length()];
+		for(int i=0;i<first.length();i++){
+			for(int j=0;j<second.length();j++){
+				if(first.charAt(i)==second.charAt(j)){
+					if(i==0||j==0){
+						mat[i][j] = 1;
+					}
+					else{
+						mat[i][j] = mat[i-1][j-1] + 1;
+					}
+					if(mat[i][j]>maxval){
+						maxval = mat[i][j];
+						maxposi = i;
+						maxposj = j;
+					}
+				}
+				else{
+					mat[i][j] = 0;
+				}
+			}
+		}
+		if(maxval>0){
+			int i=0;
+			while(true){
+				if(maxposi-i>=0 && maxposj-i>=0){
+					if(mat[maxposi-i][maxposj-i]>0){
+						result = result + String.valueOf(first.charAt(maxposi-i));
+						i++;
+					}
+					else{
+						break;
+					}
+				}
+				else{
+					break;
+				}
+			}
+			System.out.println("Longest Common Substring is: ");
+			System.out.println(new StringBuffer(result).reverse().toString());
+		}
+		else{
+			System.out.println("No Common Substring Found");
+		}
+	}
+}