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refactor: SubsetSum (#5432)

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* refactor: SubsetSum

* checkstyle: fix formatting

---------

Co-authored-by: alxkm <alx@alx.com>
This commit is contained in:
Alex Klymenko
2024-08-30 09:55:18 +02:00
committed by GitHub
parent 14916e692f
commit cd38531b0d
2 changed files with 40 additions and 30 deletions
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46
src/main/java/com/thealgorithms/dynamicprogramming/SubsetSum.java
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@ -5,46 +5,32 @@ public final 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.
* Test if a set of integers contains a subset that sums 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}.
* @param arr the array containing integers.
* @param sum the target sum of the subset.
* @return {@code true} if a subset exists that sums to the given value, otherwise {@code false}.
*/
public static boolean subsetSum(int[] arr, int sum) {
int n = arr.length;
boolean[][] isSum = new boolean[n + 2][sum + 1];
boolean[][] isSum = new boolean[n + 1][sum + 1];
isSum[n + 1][0] = true;
for (int i = 1; i <= sum; i++) {
isSum[n + 1][i] = false;
// Initialize the first column to true since a sum of 0 can always be achieved with an empty subset.
for (int i = 0; i <= n; i++) {
isSum[i][0] = true;
}
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];
// Fill the subset sum matrix
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= sum; j++) {
if (arr[i - 1] <= j) {
isSum[i][j] = isSum[i - 1][j] || isSum[i - 1][j - arr[i - 1]];
} else {
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];
return isSum[n][sum];
}
}