Reverse string (2)

Reverse string (2)

Title description

Given a character type array chas and an integer size, please move the left half of size to the right and the right half to the left.

Enter a description:

Enter two lines, the first line is an integer representing size, and the second line is a character string representing $chas(1\le size\le lengt{h}_{chas}\le 10^5)$

Output description:

Output a line of string, which represents the reversed string.

Example 1

enter

3
abcdefg

Output

defgabc

Remarks:

Time complexity $O\left(n\right)$ , additional space complexity$O\left(1\right)$。

---

answer:

First flip the left and right parts separately, and then flip the whole.

Code:

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1e5 + 10;

char s[N];

void change(int l, int r) {
    
    
    for (int i = l, j = r; i < j; ++i, --j)
        swap(s[i], s[j]);
}

int main(void) {
    
    
    int sze;
    scanf("%d", &sze);
    scanf("%s", s);
    int len = strlen(s);
    change(0, sze - 1);
    change(sze, len - 1);
    change(0, len - 1);
    puts(s);
    return 0;
}