all possible combinations of a string in java code example
Example 1: find all permutations of a string
void permute(string a, int l, int r)
{
// Base case
if (l == r)
cout<<a<<endl;
else
{
// Permutations made
for (int i = l; i <= r; i++)
{
// Swapping done
swap(a[l], a[i]);
// Recursion called
permute(a, l+1, r);
//backtrack
swap(a[l], a[i]);
}
}
}
Example 2: how to print all permutations of a string
void permutation(string s)
{
sort(s.begin(),s.end());
do{
cout << s << " ";
}
while(next_permutation(s.begin(),s.end()); // std::next_permutation
cout << endl;
}
Example 3: generate all permutations of string
void perm(char a[], int level){
static int flag[10] = {0};
static char res[10];
// If we are the last character of the input string
if(a[level] == '\0'){
// First we assign stopping point to result
res[level] = '\0';
// Now we print everything
for(int i = 0; res[i] != '\0'; ++i){
printf("%c", res[i]);
}
printf("\n");
++counter;
}
else{
// Scan the original string and flag to see what letters are available
for(int i = 0; a[i] != '\0'; ++i){
if(flag[i] == 0){
res[level] = a[i];
flag[i] = 1;
perm(a, level + 1);
flag[i] = 0;
}
}
}
}
int main(){
char first[] = "abc";
perm(first, 0);
return 0;
}
Example 4: combinations in java
private void helper(List<int[]> combinations, int data[], int start, int end, int index) {
if (index == data.length) {
int[] combination = data.clone();
combinations.add(combination);
}
else if (start <= end) {
data[index] = start;
helper(combinations, data, start + 1, end, index + 1);
helper(combinations, data, start + 1, end, index);
}
}