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Subset.java
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62 lines (53 loc) · 1.66 KB
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// abc
// a,b,c,bc,ac,abc
public class Subset {
// Using Brute Force Approach
public static void subset1(String str) {
int n = str.length();
int totalSubsets = (int) Math.pow(2, n);
for (int i = 0; i < totalSubsets; i++) {
StringBuilder subset = new StringBuilder();
// Check each bit of the number to decide inclusion of characters
for (int j = 0; j < n; j++) {
if ((i & (1 << j)) != 0) {
subset.append(str.charAt(j));
}
}
System.out.println(subset.toString());
}
}
// Using BackTracking
public static void subset2(String str, String ans, int i) {
// Base Case
if (i == str.length()) {
if (ans.length() == 0) {
System.out.println("null");
} else {
System.out.println(ans);
}
return;
}
// Yes Choice
subset2(str, ans + str.charAt(i), i + 1);
// No Choice
subset2(str, ans, i + 1);
}
// Backtracking using Stringbuilder
public static void subset3(String str, StringBuilder ans, int i) {
if (i == str.length()) {
if (ans.length() == 0) {
System.out.println("null");
} else {
System.out.println(ans);
}
return;
}
subset3(str, new StringBuilder(ans).append(str.charAt(i)), i + 1);
subset3(str, ans, i + 1);
}
public static void main(String[] args) {
subset1("abc");
StringBuilder ans = new StringBuilder();
subset3("abcd", ans, 0);
}
}