一个字符串中查找第一个只出现一次的字符。 要求复杂度为O(N).

char find_first(char *arr,int len){int asg[256] = {0};for (int i = 0; i < len; i++){asg[(int)arr[i]]++;}for (int i = 0; i < len; i++){if (asg[(int )arr[i]] == 1)return arr[i];}}int main(){char*str = "aaaaaaaccdeefddddfffffffff6";char ret=find_first(str,strlen(str));printf("%c",ret);system("pause");}