matrixChain.java

matrixChainMultiply.java

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+/* A naive recursive implementation that simply follows
+the above optimal substructure property */
+class MatrixChainMultiplication {
+	// Matrix Ai has dimension p[i-1] x p[i] for i = 1..n
+	static int MatrixChainOrder(int p[], int i, int j)
+	{
+		if (i == j)
+			return 0;
+
+		int min = Integer.MAX_VALUE;
+
+		// place parenthesis at different places between
+		// first and last matrix, recursively calculate
+		// count of multiplications for each parenthesis
+		// placement and return the minimum count
+		for (int k = i; k < j; k++)
+		{
+			int count = MatrixChainOrder(p, i, k)
+						+ MatrixChainOrder(p, k + 1, j)
+						+ p[i - 1] * p[k] * p[j];
+
+			if (count < min)
+				min = count;
+		}
+
+		// Return minimum count
+		return min;
+	}
+
+	// Driver code
+	public static void main(String args[])
+	{
+		int arr[] = new int[] { 1, 2, 3, 4, 3 };
+		int n = arr.length;
+
+		System.out.println(
+			"Minimum number of multiplications is "
+			+ MatrixChainOrder(arr, 1, n - 1));
+	}
+}
+/* This code is contributed by Rajat Mishra*/

minCost.java

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+/* A Naive recursive implementation of
+MCP(Minimum Cost Path) problem */
+public class GFG {
+
+	/* A utility function that returns
+	minimum of 3 integers */
+	static int min(int x, int y, int z)
+	{
+		if (x < y)
+			return (x < z) ? x : z;
+		else
+			return (y < z) ? y : z;
+	}
+
+	/* Returns cost of minimum cost path
+	from (0,0) to (m, n) in mat[R][C]*/
+	static int minCost(int cost[][], int m,
+									int n)
+	{
+		if (n < 0 || m < 0)
+			return Integer.MAX_VALUE;
+		else if (m == 0 && n == 0)
+			return cost[m][n];
+		else
+			return cost[m][n] +
+				min( minCost(cost, m-1, n-1),
+					minCost(cost, m-1, n),
+					minCost(cost, m, n-1) );
+	}
+
+	// Driver code
+	public static void main(String args[])
+	{
+
+		int cost[][] = { {1, 2, 3},
+						{4, 8, 2},
+						{1, 5, 3} };
+
+		System.out.print(minCost(cost, 2, 2));
+	}
+}
+
+// This code is contributed by Sam007

stringBuilder.java

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+// Java code to illustrate StringBuilder
+
+import java.util.*;
+import java.util.concurrent.LinkedBlockingQueue;
+
+public class GFG1 {
+	public static void main(String[] argv)
+		throws Exception
+	{
+
+		// create a StringBuilder object
+		// usind StringBuilder() constructor
+		StringBuilder str
+			= new StringBuilder();
+
+		str.append("GFG");
+
+		// print string
+		System.out.println("String = "
+						+ str.toString());
+
+		// create a StringBuilder object
+		// usind StringBuilder(CharSequence) constructor
+		StringBuilder str1
+			= new StringBuilder("AAAABBBCCCC");
+
+		// print string
+		System.out.println("String1 = "
+						+ str1.toString());
+
+		// create a StringBuilder object
+		// usind StringBuilder(capacity) constructor
+		StringBuilder str2
+			= new StringBuilder(10);
+
+		// print string
+		System.out.println("String2 capacity = "
+						+ str2.capacity());
+
+		// create a StringBuilder object
+		// usind StringBuilder(String) constructor
+		StringBuilder str3
+			= new StringBuilder(str1.toString());
+
+		// print string
+		System.out.println("String3 = "
+						+ str3.toString());
+	}
+}