题解 | 无限长正整数排列字符串

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

int main() {
    int n;
    scanf("%d",&n);
    char str[1010] = "";
    for(int i = 1; strlen(str) < n; i ++){
        char *strn = (char *)malloc(sizeof(char) * 4);
        if(strn == NULL){
            printf("error");
            return -1;
        }
        snprintf(strn, sizeof(strn), "%d", i);
        strcat(str,strn);
        free(strn);
    }
    printf("%c\n",str[n - 1]);
    
    return 0;
}