Reverse with Two Pointers

Lab C Intermediate 20 points

Write void reverse(int *a, int n) that uses two pointers, left (starting at the first element) and right (moved to the last one), swapping and moving them towards each other n/2 times. Reverse an input array and print it.

Input

Line 1: n. Line 2: n integers.

Output

One line.

Example

Input

5
1 2 3 4 5

Output

5 4 3 2 1

Sample input available Sample output available

Editor

Hints

Move right to the last element with right++ (n - 1 times).

Swap through the pointers, then move them inwards.

Solution explanation

Two pointers walking towards each other is a classic technique for reversing and pair-finding.

Show solution

#include <stdio.h>

void reverse(int *a, int n) {
    int *left = a;
    int *right = a;
    for (int i = 0; i < n - 1; i++) right++;
    for (int i = 0; i < n / 2; i++) {
        int t = *left;
        *left = *right;
        *right = t;
        left++;
        right--;
    }
}

int main() {
    int n, a[100];
    scanf("%d", &n);
    for (int i = 0; i < n; i++) scanf("%d", &a[i]);
    reverse(a, n);
    for (int i = 0; i < n; i++) printf("%d%s", a[i], i < n - 1 ? " " : "\n");
    return 0;
}

Output

Answer