```
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
int compare(const void * a, const void * b)
{
return strcmp(a, b);
}
struct node {
char name[51];
int index;
};
/* 1.Sort the Array cities (which was copy of A) and Array B2 (which was copy of B).
2.Do binary search in sorted array B (called B2) to find a city in A which is not present in B2.
3.If the index found is i, then print "A[i] B[i] cost[i]$".
4.Do this for n - 2 times :
For each B[indx], find it in sorted array cities and use its index(called indx) to print A[indx] B[indx] cost[indx]$ and repeat the same
*/
main()
{
int t;
scanf("%d", &t);
int n;
int c;
struct node cities[5000];// stored sorted array A with original index
char A[5000][51];
char B[5000][51];
char B2[5000][51];// stored sorted array B to find(using binary search) first city which is present in A but not in B
int cost[5000];
int total_cost;
int i, j, k;
while (t--) {
scanf("%d", &n);
if (n == 1) {
printf("0$\n");
} else {
/* Reading input - start */
for (i = 0; i < n - 1; i++) {
scanf("%s", A[i]);
cities[i].index = i;
strcpy(cities[i].name, A[i]);
scanf("%s", B[i]);
strcpy(B2[i], B[i]);
while (isspace (c = getchar()))
;
cost[i] = cost[i] * 10 + c - '0';
while (isdigit(c = getchar()))
cost[i] = cost[i] * 10 + c - '0';
}
/* Reading input - end */
/* Shell Sort starts for array "cities" and "B2"
note : original index in array "cities" is stored*/
int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
for (k = 0; k < 8; k++)
for (i = gaps[k]; i < n - 1; ++i) {
char temp[51];
strcpy(temp, cities[i].name);
int ind = cities[i].index;
for (j = i; j >= gaps[k] && strcmp(cities[j-gaps[k]].name, temp) > 0; j -= gaps[k]) {
strcpy(cities[j].name, cities[j-gaps[k]].name);
cities[j].index = cities[j-gaps[k]].index;
}
strcpy(cities[j].name, temp);
cities[j].index = ind;
char temp2[51];
strcpy(temp2, B2[i]);
for (j = i; j >= gaps[k] && strcmp(B2[j-gaps[k]], temp2) > 0; j -= gaps[k])
strcpy(B2[j], B2[j-gaps[k]]);
strcpy(B2[j], temp2);
}
for (i = 0; i < n - 1; i++) {
char *t = (char *)bsearch(A[i], B2[0], n-1, sizeof(char[51]), compare);
if (t == NULL)
break;
}
printf("%s %s %d$\n", A[i], B[i], cost[i]);
total_cost = cost[i];
int low, high, mid, indx;
indx = i;
for (i = 0; i < n - 2; i++) {
low = 0;
high = n - 2;
while (low <= high) {
mid = (low+high) / 2;
if (strcmp(B[indx], cities[mid].name) < 0)
high = mid - 1;
else if (strcmp(B[indx], cities[mid].name) > 0)
low = mid + 1;
else
break;
}
indx = cities[mid].index;
total_cost += cost[indx];
printf("%s %s %d$\n", A[indx], B[indx], cost[indx]);
}
printf("%d$\n", total_cost);
for (i = 0; i < n - 1; i++)
cost[i] = 0;
}}
return 0;
}
```

The question can be found Here