uploading pending code

Author: Algorithmica

2017-september/12.string problems/src/com/alg/top20/palsubstr/LongPalSubString.java

@@ -50,14 +50,37 @@ public static int longPalSubstr2(String s) {
 		printMemory(mem);
 		return max;
 	}
+	//TC:O(n^2)
+	//SC:O(1) 
+	//Expand around each index as centre
+	public static int longPalSubstr3(String s) {
+		int max = 0;
+		for(int i = 0; i < s.length(); ++i) {
+			int odd = expandCenter(i, i, s);
+			int even = expandCenter(i, i+1, s);
+			max = Math.max(max, Math.max(odd, even));
+		}
+		return max;
+	}
+	private static int expandCenter(int l, int r, String s) {
+		while(l >= 0 && r < s.length()) {
+			if(s.charAt(l) == s.charAt(r)) {
+				--l;
+				++r;
+			} else
+				break;
+		}
+		return r-l-1;
+	}
 
 	private static void printMemory(boolean[][] mem) {
 		for(boolean[] tmp: mem)
 			System.out.println(Arrays.toString(tmp));
 	}
 
 	public static void main(String[] args) {
-		System.out.println(longPalSubstr2(args[0]));
+		//System.out.println(longPalSubstr2(args[0]));
+		System.out.println(longPalSubstr3(args[0]));
 	}
 
 }

2017-september/12.string problems/src/com/alg/top20/palsubstr/PalSubString.java

@@ -0,0 +1,24 @@
+package com.alg.top20.bittricks;
+
+public class AllSubsets {
+
+	public static void allSubsets(int[] in) {
+		int n = in.length;
+		int limit = 1 << n;
+		for(int i = 0; i < limit; ++i) {
+			for(int j = 1; j <= n; ++j) {
+				if( (i & (1<<j-1)) != 0)
+					System.out.print(in[j-1]+" ");
+			}
+			System.out.println();
+		}
+	}
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		int[] in = new int[n];
+		for(int i = 0; i < n; ++i)
+			in[i] = i+10;
+		allSubsets(in);
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/AllSubsets.java

@@ -0,0 +1,22 @@
+package com.alg.top20.bittricks;
+
+public class BitWiseUtilities {
+	
+	public static void display(int n) {
+		int mask = 1 << 31;
+		for(int i = 0; i < 32; ++i) {
+			if((n & mask) != 0) 
+				System.out.print("1");
+			else
+				System.out.print("0");
+			mask = mask >>> 1;
+		}
+		System.out.println();
+	}
+	
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		display(n);
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/BitWiseUtilities.java

@@ -0,0 +1,43 @@
+package com.alg.top20.bittricks;
+
+public class CountOnes {
+
+	public static int countOnes1(int n) {
+		int mask = 1 << 31;
+		int count = 0;
+		for(int i = 0; i < 32; ++i) {
+			if((n & mask) != 0) 
+				++count;
+			mask = mask >>> 1;
+		}
+		return count;
+	}
+	
+	public static int countOnes2(int n) {
+		int mask = 0xF;
+		int count = 0;
+		int[] ones = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4};
+		while(n > 0) {
+			count = count + ones[(n & mask)]; 
+			n = n >>> 4;
+		}
+		return count;
+	}
+	
+	public static int countOnes3(int n) { 
+		int count = 0;
+		while(n > 0) {
+			++count;
+			n = n & (n-1);
+		}
+		return count;
+	}
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		BitWiseUtilities.display(n);
+		System.out.println(countOnes1(n));
+		System.out.println(countOnes2(n));
+		System.out.println(countOnes3(n));
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/CountOnes.java

@@ -0,0 +1,13 @@
+package com.alg.top20.bittricks;
+
+public class EvenOddCheck {
+
+	public static boolean isOdd(int n) {
+		return (n & 1) != 0;
+	}
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/EvenOddCheck.java

@@ -0,0 +1,18 @@
+package com.alg.top20.bittricks;
+
+public class HigherLowerMultiples {
+
+	public static int nextHighestMult8(int n) {
+		return (n+7) & ~7;
+	}
+	
+	public static int prevLowestMult8(int n) {
+		return n & ~7;
+	}
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		System.out.println(prevLowestMult8(n));
+		System.out.println(nextHighestMult8(n));
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/HigherLowerMultiples.java

@@ -0,0 +1,20 @@
+package com.alg.top20.bittricks;
+
+public class IPAddress {
+	
+	public static int getNetworkId(int n) {
+		int mask = 0xFF000000;
+		return (n & mask) >>> 24;
+	}
+	public static int getHostId(int n) {
+		int mask = 0xFFFFFF;
+		return n & mask;
+	}
+	
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		BitWiseUtilities.display(n);
+		System.out.println(getNetworkId(n));
+		System.out.println(getHostId(n));
+	}
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/IPAddress.java

@@ -0,0 +1,15 @@
+package com.alg.top20.bittricks;
+
+public class IsPowerOf2 {
+
+	public static boolean isPowerOf2(int n) {
+		return (n & (n-1)) == 0;
+	}
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		BitWiseUtilities.display(n);
+		System.out.println(isPowerOf2(n));
+
+	}
+
+}

2017-september/15.bitwise tricks/src/com/alg/top20/bittricks/IsPowerOf2.java

@@ -0,0 +1,29 @@
+package com.alg.top20.bittricks;
+
+public class Operators {
+	
+	public static int set(int n, int k) {
+		n = n | (1<<k-1);
+		return n;
+	}
+	
+	public static int clear(int n, int k) {
+		n = n & ~(1<<k-1);
+		return n;
+	}
+	
+	public static int toggle(int n, int k) {
+		n = n ^ (1<<k-1);
+		return n;
+	}
+	
+	public static void main(String[] args) {
+		int n = Integer.parseInt(args[0]);
+		BitWiseUtilities.display(n);
+		BitWiseUtilities.display(set(n, 20));
+		BitWiseUtilities.display(toggle(n, 4));
+		BitWiseUtilities.display(toggle(n, 3));
+		BitWiseUtilities.display(clear(n, 2));
+	}
+
+}