Initial data commit

Task/Matrix-chain-multiplication/Java/matrix-chain-multiplication.java

@@ -0,0 +1,60 @@
+import java.util.Arrays;
+
+public class MatrixChainMultiplication {
+
+    public static void main(String[] args) {
+        runMatrixChainMultiplication(new int[] {5, 6, 3, 1});
+        runMatrixChainMultiplication(new int[] {1, 5, 25, 30, 100, 70, 2, 1, 100, 250, 1, 1000, 2});
+        runMatrixChainMultiplication(new int[] {1000, 1, 500, 12, 1, 700, 2500, 3, 2, 5, 14, 10});
+    }
+
+    private static void runMatrixChainMultiplication(int[] dims) {
+        System.out.printf("Array Dimension  = %s%n", Arrays.toString(dims));
+        System.out.printf("Cost             = %d%n", matrixChainOrder(dims));
+        System.out.printf("Optimal Multiply = %s%n%n", getOptimalParenthesizations());
+    }
+
+    private static int[][]cost;
+    private static int[][]order;
+
+    public static int matrixChainOrder(int[] dims) {
+        int n = dims.length - 1;
+        cost = new int[n][n];
+        order = new int[n][n];
+
+        for (int lenMinusOne = 1 ; lenMinusOne < n ; lenMinusOne++) {
+            for (int i = 0; i < n - lenMinusOne; i++) {
+                int j = i + lenMinusOne;
+                cost[i][j] = Integer.MAX_VALUE;
+                for (int k = i; k < j; k++) {
+                    int currentCost = cost[i][k] + cost[k+1][j] + dims[i]*dims[k+1]*dims[j+1];
+                    if (currentCost < cost[i][j]) {
+                        cost[i][j] = currentCost;
+                        order[i][j] = k;
+                    }
+                }
+            }
+        }
+        return cost[0][n-1];
+    }
+
+    private static String getOptimalParenthesizations() {
+        return getOptimalParenthesizations(order, 0, order.length - 1);
+    }
+
+    private static String getOptimalParenthesizations(int[][]s, int i, int j) {
+        if (i == j) {
+            return String.format("%c", i+65);
+        }
+        else {
+            StringBuilder sb = new StringBuilder();
+            sb.append("(");
+            sb.append(getOptimalParenthesizations(s, i, s[i][j]));
+            sb.append(" * ");
+            sb.append(getOptimalParenthesizations(s, s[i][j] + 1, j));
+            sb.append(")");
+            return sb.toString();
+        }
+    }
+
+}