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Created SubsetSum.java
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57
DynamicProgramming/SubsetSum.java
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57
DynamicProgramming/SubsetSum.java
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package DynamicProgramming;
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public class SubsetSum {
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/*
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This algorithm will determine if a set of integers contains
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a subset that sum to a given integer. The algorithm will
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return true if such a subset exists and false otherwise.
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This is a dynamic programming implementation.
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*/
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private static boolean subsetSum(int arr[], int n, int sum){
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boolean isSum[][] = new boolean[n + 2][sum + 1];
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isSum[n + 1][0] = true;
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for (int i = 1; i <= sum; i++) {
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isSum[n + 1][i] = false;
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}
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for (int i = n; i > 0; i--) {
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isSum[i][0] = true;
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for (int j = 1; j <= arr[i - 1] - 1; j++) {
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if (j <= sum) {
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isSum[i][j] = isSum[i + 1][j];
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}
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}
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for (int j = arr[i - 1]; j <= sum; j++) {
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isSum[i][j] = (isSum[i + 1][j] || isSum[i + 1][j - arr[i - 1]]);
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}
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}
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return isSum[1][sum];
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}
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/*
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This is a driver method to run the algorithm with four
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test values: the first two should evaluate true, and the
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last two should evaluate false.
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*/
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public static void main(String args[]) {
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int arr[] = new int[]{50, 4, 10, 15, 34};
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int n = arr.length;
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// 4 + 10 + 15 + 34 = 64
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int sum1 = 64;
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// 50 + 15 + 34 = 99
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int sum2 = 99;
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// No subset of the given array will give a sum
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// of 5 or 66
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int sum3 = 5;
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int sum4 = 66;
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System.out.println(subsetSum(arr, n, sum1));
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System.out.println(subsetSum(arr, n, sum2));
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System.out.println(subsetSum(arr, n, sum3));
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System.out.println(subsetSum(arr, n, sum4));
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}
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}
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