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Merged
merged 2 commits into from
Sep 22, 2020
Merged

Created SubsetSum.java #1473

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c41d10a
Created SubsetSum.java
Sep 20, 2020
e5a3e4b
reformat code
realDuYuanChao Sep 22, 2020
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46 changes: 46 additions & 0 deletions DynamicProgramming/SubsetSum.java
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Original file line number Diff line number Diff line change
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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];
}
}