Program #22 (U3): Reverse an Array In-Place (two pointers)
Task: Read N and the array, then swap elements from both ends moving inward. Print the reversed array.
#include <stdio.h>
void reverse(int a[], int n) {
int i = 0, j = n - 1, t;
while (i < j) { t = a[i]; a[i] = a[j]; a[j] = t; ++i; --j; }
} int main(void) {
int N, a[200];
printf("Enter N (1..200): ");
if (scanf("%d", &N) != 1 || N <= 0 || N > 200) { printf("Invalid N.\n"); return 0; }
printf("Enter %d integers: ", N);
for (int i = 0; i < N; ++i) scanf("%d", &a[i]);
reverse(a, N); printf("Reversed: ");
for (int i = 0; i < N; ++i) printf("%d ", a[i]);
printf("\n");
return 0;
}