Permutations of Strings

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  • + 0 comments

    Here is Permutations of Strings solution in c - https://programmingoneonone.com/hackerrank-permutations-of-strings-solution-in-c.html

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    include

    include

    include

    int next_permutation(int n, char **s) { int k = -1; for (int i = 0; i < n - 1; i++) { if (strcmp(s[i], s[i + 1]) < 0) { k = i; } } if (k == -1) { return 0; // No next permutation }

    // Step 2: Find the largest index l greater than k such that s[k] < s[l]
    int l = -1;
    for (int i = k + 1; i < n; i++) {
        if (strcmp(s[k], s[i]) < 0) {
            l = i;
        }
    }
    
    // Step 3: Swap the value of s[k] with that of s[l]
    char *temp = s[k];
    s[k] = s[l];
    s[l] = temp;
    
    // Step 4: Reverse the sequence from s[k + 1] to s[n - 1]
    for (int i = k + 1, j = n - 1; i < j; i++, j--) {
        temp = s[i];
        s[i] = s[j];
        s[j] = temp;
    }
    
    return 1; // Next permutation exists
    

    }

    int main() { char **s; int n; scanf("%d", &n); s = calloc(n, sizeof(char*)); for (int i = 0; i < n; i++) { s[i] = calloc(11, sizeof(char)); scanf("%s", s[i]); } do { for (int i = 0; i < n; i++) printf("%s%c", s[i], i == n - 1 ? '\n' : ' '); } while (next_permutation(n, s)); for (int i = 0; i < n; i++) free(s[i]); free(s); return 0; }

  • + 0 comments

    Tried to make is as simple as possible

    void reverse(char **s, int start, int end) {
        while (start < end) {
            char *temp = s[start];
            s[start] = s[end];
            s[end] = temp;
            start++;
            end--;
        }
    }
    
    int next_permutation(int n, char **s)
    {
        int i = n - 2;
        while (i >= 0 && strcmp(s[i], s[i + 1]) >= 0) i--; 
        
        if (i < 0) return 0;
        
        int j = n - 1;
        while (strcmp(s[i], s[j]) >= 0) j--; 
        
        char *temp = s[i];
        s[i] = s[j];
        s[j] = temp;
        
        reverse(s, i + 1, n - 1);
        
        return 1;
    }
    
  • + 1 comment

    This is a horrible question.

  • + 1 comment
     // Step 1: Find the largest index k such that s[k] < s[k + 1]
        int k = -1;
        for (int i = 0; i < n - 1; i++) {
            if (strcmp(s[i], s[i + 1]) < 0) {
                k = i;
            }
        }
        if (k == -1) {
            return 0; // No next permutation
        }
    
        // Step 2: Find the largest index l greater than k such that s[k] < s[l]
        int l = -1;
        for (int i = k + 1; i < n; i++) {
            if (strcmp(s[k], s[i]) < 0) {
                l = i;
            }
        }
    
        // Step 3: Swap the value of s[k] with that of s[l]
        char *temp = s[k];
        s[k] = s[l];
        s[l] = temp;
    
        // Step 4: Reverse the sequence from s[k + 1] to s[n - 1]
        for (int i = k + 1, j = n - 1; i < j; i++, j--) {
            temp = s[i];
            s[i] = s[j];
            s[j] = temp;
        }
    
        return 1; // Next permutation exists