#13 Implement coverage tool for Knapsack

src/main/java/com/williamfiset/algorithms/dp/Knapsack_01.java

@@ -13,6 +13,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.*;
 
 public class Knapsack_01 {
 
@@ -23,30 +24,41 @@ public class Knapsack_01 {
    * @return The maximum achievable profit of selecting a subset of the elements such that the
    *     capacity of the knapsack is not exceeded
    */
-  public static int knapsack(int capacity, int[] W, int[] V) {
+  public static int knapsack(int capacity, int[] W, int[] V, int[] branches) {
 
+    // These cases should be tested to improve the coverage
     if (W == null || V == null || W.length != V.length || capacity < 0)
       throw new IllegalArgumentException("Invalid input");
 
+
     final int N = W.length;
 
     // Initialize a table where individual rows represent items
     // and columns represent the weight of the knapsack
     int[][] DP = new int[N + 1][capacity + 1];
 
+    // Covered by "test" in main
     for (int i = 1; i <= N; i++) {
+      branches[4] = 1;
 
       // Get the value and weight of the item
       int w = W[i - 1], v = V[i - 1];
 
+      // Covered by "test" in main
       for (int sz = 1; sz <= capacity; sz++) {
+        branches[5] = 1;
 
         // Consider not picking this element
         DP[i][sz] = DP[i - 1][sz];
 
         // Consider including the current element and
         // see if this would be more profitable
-        if (sz >= w && DP[i - 1][sz - w] + v > DP[i][sz]) DP[i][sz] = DP[i - 1][sz - w] + v;
+        // Covered by "test" in main
+        if (sz >= w && DP[i - 1][sz - w] + v > DP[i][sz]) {
+          branches[6] = 1;
+          branches[7] = 1;
+          DP[i][sz] = DP[i - 1][sz - w] + v;
+        }
       }
     }
 
@@ -56,8 +68,12 @@ public static int knapsack(int capacity, int[] W, int[] V) {
     // Using the information inside the table we can backtrack and determine
     // which items were selected during the dynamic programming phase. The idea
     // is that if DP[i][sz] != DP[i-1][sz] then the item was selected
+    // Covered by "test" in main
     for (int i = N; i > 0; i--) {
+      branches[8] = 1;
+      // Covered by "test" in main
       if (DP[i][sz] != DP[i - 1][sz]) {
+        branches[9] = 1;
         int itemIndex = i - 1;
         itemsSelected.add(itemIndex);
         sz -= W[itemIndex];
@@ -72,16 +88,36 @@ public static int knapsack(int capacity, int[] W, int[] V) {
     return DP[N][capacity];
   }
 
+
+  public static void showCoverage(int[] branches) {
+    for (int i=0; i < branches.length; i++) {
+      System.out.println((i+1) + ": " + branches[i]);
+    }
+    double sum = IntStream.of(branches).sum();
+    System.out.println("Branch coverage: " + Math.floor((sum+1)/11*100) + "%" );
+  }
+
+
+  public static void branchesForExceptions(int[] branches, int capacity, int[] W, int[] V) {
+    if (W == null) branches[0] = 1;
+    if (V == null) branches[1] = 1;
+    if (W.length != V.length) branches[2] = 1;
+    if (capacity < 0) branches[3] = 1;
+  }
+
   public static void main(String[] args) {
+    int[] branches = new int[10];
 
     int capacity = 10;
     int[] V = {1, 4, 8, 5};
     int[] W = {3, 3, 5, 6};
-    System.out.println(knapsack(capacity, W, V));
+    System.out.println(knapsack(capacity, W, V, branches));
 
-    capacity = 7;
+    /*capacity = 7;
     V = new int[] {2, 2, 4, 5, 3};
     W = new int[] {3, 1, 3, 4, 2};
-    System.out.println(knapsack(capacity, W, V));
+    System.out.println(knapsack(capacity, W, V, branches));*/
+
+    showCoverage(branches);
   }
 }