Given a string, find all of its permutations

1____void find_permutations(string s, int i, int n, bool check_duplicate) {
2__________if (i >= n) {
3________________cout << s << " ";
4__________} else {
5________________bool ch[256];
6________________for (int j=0; j<256; j++) ch[j] = false;
7________________for (int j=i; j<n; j++) {
8______________________if (!ch[s[j]] || !check_duplicate) {
9____________________________ch[s[j]] = true;
10___________________________swap(s[i], s[j]);
11___________________________find_permutations(s, i+1, n, check_duplicate);
12___________________________swap(s[i], s[j]);
13_____________________}____________
14_______________}
15_________}
16___}

Hi I'm not sure about the arguments in the method

does i begin from 0 and n is the length of the string s?
Also what is the boolean check_duplicate?

viterbi wrote:1____void find_permutations(string s, int i, int n, bool check_duplicate) {
2__________if (i >= n) {
3________________cout << s << " ";
4__________} else {
5________________bool ch[256];
6________________for (int j=0; j<256; j++) ch[j] = false;
7________________for (int j=i; j<n; j++) {
8______________________if (!ch[s[j]] || !check_duplicate) {
9____________________________ch[s[j]] = true;
10___________________________swap(s[i], s[j]);
11___________________________find_permutations(s, i+1, n, check_duplicate);
12___________________________swap(s[i], s[j]);
13_____________________}____________
14_______________}
15_________}
16___}

Sorry, I should write some explanation. Yes, you call it with i=0 and n is the length of the string. check_duplicate means to out put the same string twice if there is duplicate characters.

For example, "aab", if check duplicate, all permutations are aab, aba, baa,
if not, then aab, aab, aba, aba, baa, baa.

skyboard wrote:Hi I'm not sure about the arguments in the method

does i begin from 0 and n is the length of the string s?
Also what is the boolean check_duplicate?

viterbi wrote:1____void find_permutations(string s, int i, int n, bool check_duplicate) {
2__________if (i >= n) {
3________________cout << s << " ";
4__________} else {
5________________bool ch[256];
6________________for (int j=0; j<256; j++) ch[j] = false;
7________________for (int j=i; j<n; j++) {
8______________________if (!ch[s[j]] || !check_duplicate) {
9____________________________ch[s[j]] = true;
10___________________________swap(s[i], s[j]);
11___________________________find_permutations(s, i+1, n, check_duplicate);
12___________________________swap(s[i], s[j]);
13_____________________}____________
14_______________}
15_________}
16___}