To find the max palindrome in a given string

#include <iostream>
#include <string>
#include <assert.h>

using namespace std;

/*
 * Algo:
 *  find the sequence where two equal letters are adjacent or apart by one letter
 *      example: "aa", "aba"
 *  expand the sequence while the letters at prev and next of the sequence are equal
 *
 *  maintain the max palindrome encountered  so far
 *
 *  Complexity: best O(n) and worst O(n^2)
 */

string largestPalindrome(string s) {

    int i, j, k, len = s.length(), m = 0;
    string ret(1, s[0]);

    for (i = 1; i < len; ++i) {

        if (s[i - 1] == s[i]) {

            j = i - 2;
            k = i + 1;

            //expand the sequence
            while (j >= 0 && k < len && s[j] == s[k]) {
                j--, k++;
            }

            //compare with prev max
            if (m < (k - j - 1) ) {
                m = k - j - 1;
                ret = s.substr(j + 1, m);
            }
        }

        if ( (i + 1 < len) && s[i - 1] == s[i + 1]) {

            j = i - 2;
            k = i + 2;

            //expand the sequence
            while (j >= 0 && k < len && s[j] == s[k]) {
                j--, k++;
            }

            //compare with prev max
            if (m < (k - j - 1) ) {
                m = k - j - 1;
                ret = s.substr(j + 1, m);
            }
        }
    }

    return ret;
}

int main() {
    assert(largestPalindrome("a") == "a");
    assert(largestPalindrome("sa") == "s");
    assert(largestPalindrome("aa") == "aa");
    assert(largestPalindrome("aaa") == "aaa");
    assert(largestPalindrome("aba") == "aba");
    assert(largestPalindrome("abba") == "abba");
    assert(largestPalindrome("aaaa") == "aaaa");
    assert(largestPalindrome("aaaaa") == "aaaaa");
    assert(largestPalindrome("aabaa") == "aabaa");
    assert(largestPalindrome("sambasiva") == "s");
    assert(largestPalindrome("sambabmiv") == "mbabm");
    assert(largestPalindrome("saaasr") == "saaas");
    assert(largestPalindrome("saasr") == "saas");

    cout<< "All tests passed" << endl;
}

To print all the paths the frog can choose to cross the river

Problem

#include <stdio.h>

int frogPaths(int res[], int resIndex, int curRock, int numRocks) {
    if (curRock == numRocks) {

        int i;

        for (i = 0; i < resIndex; ++i) {
            printf("%d ", res[i]);
        }
        printf("%d\n", curRock);

        return 1;

    } else {
        int count = 0;

        res[resIndex] = curRock;

        if (curRock + 1 <= numRocks)
            count += frogPaths(res, resIndex + 1, curRock + 1, numRocks);

        if (curRock + 2 <= numRocks)
            count += frogPaths(res, resIndex + 1, curRock + 2, numRocks);

        return count;
    }
}


int main(){
    int n;

    scanf("%d", &n);

    int a[n + 1];

    printf("Total num of paths = %d\n",frogPaths(a, 0, 1, n));
}