多个字符从两端移动，向中间汇聚

#include<stdio.h>
#include<string.h>

int main() {
  char arr1[] = "welcome to bit!!!!!";
  char arr2[] = "###################";
  int left = 0;
  int max = strlen(arr1);
  int right = max - 1;

  while (left<=right+2){
    printf("%s\n", arr2);
    arr2[left] = arr1[left];
    arr2[right] = arr1[right];
    right--;
    left++;
  }
  return 0;
}