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CountSubsetWithSumK.java
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CountSubsetWithSumK.java
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package Dynamic_Programming;
import java.util.Arrays;
public class CountSubsetWithSumK {
// Recursion
public static int funRec(int[] arr, int k, int n){
if (k==0) return 1;
if (n==0) {
if (arr[0] == k) return 1;
else return 0;
}
int take = 0;
if (arr[n] <= k) take = funRec(arr, k-arr[n], n-1);
int notTake = funRec(arr, k, n-1);
return take + notTake;
}
// Memoization
public static int funMemo(int[] arr, int n, int k, int[][] dp){
if (n==0){
if (arr[0] == k) return 1;
else return 0;
}
if (k==0) return 1;
if (dp[n][k] != -1) return dp[n][k];
int take = 0;
if (arr[n] <= k) take = funMemo(arr, n-1, k-arr[n], dp);
int notTake = funMemo(arr, n-1, k, dp);
return dp[n][k] = take + notTake;
}
public static int funTab(int[] arr, int target){
int n = arr.length;
int[][] dp = new int[n][target+1];
// initialize array
// when k == 0 1st row all ONE
for (int i=0; i<n; i++){
dp[i][0] = 1;
}
if (arr[0] <= target) {
dp[0][arr[0]] = 1;
}
for (int i=1; i<dp.length; i++){
for (int j=1; j<dp[0].length; j++){
int take = 0;
if (arr[i] <= j) take = dp[i-1][j-arr[i]];
int notTake = dp[i-1][j];
dp[i][j] = take + notTake;
}
}
return dp[n-1][target];
}
public static void main(String[] args) {
int[] arr = {1 , 2, 2, 3};
int K = 3;
int n = arr.length;
System.out.println(funRec(arr, K, n-1));
int[][] dp = new int[n][K+1];
for (int i=0; i<dp.length; i++){
Arrays.fill(dp[i], -1);
}
System.out.println(funMemo(arr, n-1, K, dp));
System.out.println(funTab(arr, K));
}
}