#include <iostream>#include <cstdio>#include <cstring>using namespace std;void reverse_string(int a,int b,char str[]){    int n=(b-a+1)/2;    for(int i=0;i<n;i++){        char t=str[a+i];        str[a+i]=str[b-i];        str[b-i]=t;    }}int main(){    int n,s;    char a[1000];    printf("Please input the substring‘s length.\n");    scanf("%d",&s);    printf("Please input the string .\n");    scanf("%s",a);    n=strlen(a);    reverse_string(0,s-1,a);    reverse_string(s,n-1,a);    reverse_string(0,n-1,a);    printf("%s",a);    return 0;}