Merge pull request TheAlgorithms#1473 from jessedadams/add-jesse-adams

realDuYuanChao · web-flow · commit cfbd62999429 · 2020-09-22T10:11:39.000+08:00
Created SubsetSum.java
diff --git a/DynamicProgramming/SubsetSum.java b/DynamicProgramming/SubsetSum.java
@@ -0,0 +1,46 @@
+package DynamicProgramming;
+
+public class SubsetSum {
+
+    /**
+     * Driver Code
+     */
+    public static void main(String[] args) {
+        int[] arr = new int[]{50, 4, 10, 15, 34};
+        assert subsetSum(arr, 64); /* 4 + 10 + 15 + 34 = 64 */
+        assert subsetSum(arr, 99); /* 50 + 15 + 34 = 99 */
+        assert !subsetSum(arr, 5);
+        assert !subsetSum(arr, 66);
+    }
+
+    /**
+     * Test if a set of integers contains a subset that sum to a given integer.
+     *
+     * @param arr the array contains integers.
+     * @param sum target sum of subset.
+     * @return {@code true} if subset exists, otherwise {@code false}.
+     */
+    private static boolean subsetSum(int[] arr, int sum) {
+        int n = arr.length;
+        boolean[][] isSum = new boolean[n + 2][sum + 1];
+
+        isSum[n + 1][0] = true;
+        for (int i = 1; i <= sum; i++) {
+            isSum[n + 1][i] = false;
+        }
+
+        for (int i = n; i > 0; i--) {
+            isSum[i][0] = true;
+            for (int j = 1; j <= arr[i - 1] - 1; j++) {
+                if (j <= sum) {
+                    isSum[i][j] = isSum[i + 1][j];
+                }
+            }
+            for (int j = arr[i - 1]; j <= sum; j++) {
+                isSum[i][j] = (isSum[i + 1][j] || isSum[i + 1][j - arr[i - 1]]);
+            }
+        }
+
+        return isSum[1][sum];
+    }
+}
