NOTIFICATION: These examples are provided for educational purposes. Using this code is under your own responsibility and risk. The code is given ‘as is’. I do not take responsibilities of how they are used.

```/**
* @author: Alejandro G. Carlstein R. M.
*/
#include <stdio.h>

/* Macros Functions */
#define max(a,b) \
({ typeof (a) _a = (a); \
typeof (b) _b = (b); \
_a > _b ? _a : _b; })

/* Debugging flags */
#define DBG_LV1 0
#define DBG_LV2 1
#define DBG_LV3 0

/* Constants */
#define MAX_NUM_CAR 100
#define MAX_FERRY_LEN 100

enum{ UNKNOWN = -1, LEFT = 0, RIGHT = 1,
};

/* Our dynamic programming table element.  We have the value
* that we can store, and also a way to remember what we selected.
*/
typedef struct{
int length;
int prev_row;
int prev_col;
} Table;

int cars[MAX_NUM_CAR];
int side[MAX_NUM_CAR];
int i, j;
int ferry_len;
int total_cars;

// [ROW] [COLUMN]
Table ferry[MAX_FERRY_LEN][MAX_FERRY_LEN];

/*
*
*/
int main(int argc, char *argv[]){

/* Read the length of the ferry */
scanf('%d', &ferry_len);

// Read length of each car and set side to UNKNOWN since
// we haven't decided yet where they will go
cars[0] = 0;
side[0] = UNKNOWN;
for (i = 1; scanf('%d', &cars[i]) == 1; ++i){
side[i] = UNKNOWN;
};
total_cars = i;

// Initialize the first row and the first column
for (i = 0; i <= ferry_len; ++i)
ferry[0][i].length = ferry[i][0].length = 0;
ferry[0][i].prev_row = ferry[i][0].prev_col = 0;

// Print info
if (DBG_LV2){
printf('\nLength of Ferry: %d \n', ferry_len);
printf('Number of Cars: %d \n\n', total_cars);

for (i = 0; i < total_cars; ++i)
printf('Car[%d]: %d length\n',
i, cars[i]);
printf('************************************\n');
}//end if

// Fill table
int result = recursive_ferry(0,0,0, ferry_len);

if (DBG_LV2){
printf('Result: %d length value\n',  result);
}

if (DBG_LV2)
print_tables();

// Track back foot steps
if (DBG_LV2)  printf('tracking(%d, %d, %d)\n\n', ferry_len, ferry_len, total_cars);
tracking(ferry_len, ferry_len, total_cars);

// Print results
if (DBG_LV2) printf('\n SIDE: \n');

for (i = 1; i < total_cars; ++i)
switch(side[i]){
case UNKNOWN:
if (DBG_LV2) printf('UNKNOWN side[%d]: %d\n', i, side[i]);
break;

case RIGHT:
if (DBG_LV2) printf('RIGHT side[%d]: %d\n', i, side[i]);
printf('right\n');
break;

case LEFT:
if (DBG_LV2) printf('LEFT side[%d]: %d\n', i, side[i]);
printf('left\n');
break;

};

return 0;
}

/*
*
*/
int tracking(int left, int right, int idx_car){

if (1) printf('\ntracking(%d,%d,%d)\n', left, right, idx_car);

if (idx_car < 0)
return;

if (DBG_LV2) printf('.1 ');

if (ferry[left][right].length == 0)
return;

if (DBG_LV2) printf('.2 ');

--idx_car;

int prev_len = (left + right) - cars[idx_car];
int prev_left = left - cars[idx_car];
int prev_right = right - cars[idx_car];

if (DBG_LV2) printf('prev_len: %d = (%d + %d) - %d (car[%d])\n', prev_len, left, right, cars[idx_car], idx_car);

if (ferry[prev_left][right].length == prev_len && prev_left >= 0){

if (DBG_LV2) printf('ferry[prev_LEFT: %d][right: %d] MATCH [from RIGHT]\n', prev_left, right);

side[idx_car] = RIGHT;

tracking (prev_left, right, idx_car);

}else  if (ferry[left][prev_right].length == prev_len && prev_right >= 0){

if (DBG_LV2) printf('ferry[left: %d][prev_RIGHT: %d] MATCH [from LEFT]\n', left, prev_right);

side[idx_car] = LEFT;

tracking (left, prev_right, idx_car);

}else{

if (DBG_LV2) printf('ferry[prev_left][right] and ferry[left][prev_right] DO NOT MATCH\n');
tracking (left, right, idx_car);

}//end if

return;
}

/*
*
*/
int recursive_ferry(int left, int right, int idx_car, int ferry_len){

if (DBG_LV1) printf('r_f(left: %d, right: %d, idx_car: %d (car_len: %d) \n',
left, right, idx_car, cars[idx_car]);

if (left > ferry_len || right > ferry_len || idx_car > total_cars)
return 0;

if (ferry[left][right].length > 0){
if (DBG_LV3) printf('++Return length: %d \n', ferry[left][right].length);
return ferry[left][right].length;
}// end if

// Store value in ferry
ferry[left][right].length += (left + right);

// Record foot steps
int nxt_row = ferry[left][right].prev_row = left;
int nxt_col = ferry[left][right].prev_col = right;

//
int rtn_left = recursive_ferry(left + cars[idx_car], right, idx_car + 1, ferry_len);
int rtn_right = recursive_ferry(left, right + cars[idx_car], idx_car + 1, ferry_len);

if (DBG_LV1 && (rtn_left == 0))
printf('L>');

if (DBG_LV1)
printf('[%d,%d](%d | %d)', nxt_row, nxt_col, rtn_left, rtn_right);

if (DBG_LV1 && (rtn_right == 0))
printf('<R');

if (DBG_LV2) printf('\n');
// Obtain the result of the best route
return max(rtn_left, rtn_right);
}

/*
*
*/
int print_tables(void){

printf('\n\nTABLE\n ');
for (i = 0; i <= ferry_len; ++i)
printf(' %d ',i);
printf('\n');

for (i = 0; i <= ferry_len; ++i){
for (j = 0; j <= ferry_len; ++j){
if (j == 0) printf('%d', i);
printf (' %d ', ferry[i][j].length);
}// end for
printf('\n');
}//end for
printf('\n');

printf('\n TABLE XY\n ');
for (i = 0; i <= ferry_len; ++i)
printf(' [ %d ]',i);
printf('\n');

for (i = 0; i <= ferry_len; ++i){
for (j = 0; j <= ferry_len; ++j){
if (j == 0) printf('%d ', i);
printf('[%d,%d] ', ferry[i][j].prev_row, ferry[i][j].prev_col);
}//end for
printf('\n');
}//end for
printf('\n');

return 0;
}```

If you encounter any problems or errors, please let me know by providing an example of the code, input, output, and an explanation. Thanks.