题目:给你两个二进制字符串 a
和 b
,以二进制字符串的形式返回它们的和。
示例 1:
输入:a = "11", b = "1" 输出:"100"
示例 2:
输入:a = "1010", b = "1011" 输出:"10101"
//翻转字符串
void reverse(char* a)
{
int len = strlen(a);
int i;
for(i=0;i<len/2;i++)
{
char temp = a[i];
a[i] = a[len-i-1];
a[len-i-1] = temp;
}
}
char* addBinary(char* a, char* b) {
int len1=strlen(a);
int len2=strlen(b);
int n = (int)fmax(len1,len2);
reverse(a);
reverse(b);
int i,carry=0;
//记住一定要多分配两个内存(n+2),一个留给进位,一个给'\0',否则会导致内存越界,执行出错!
char* result = (char*)malloc(sizeof(char)*(n+2));
//从低位到高位按位相加
for(i=0;i<n;i++)
{
carry += i < len1 ? (a[i]=='1') : 0;
carry += i < len2 ? (b[i]=='1') : 0;
result[i] = carry % 2 + '0';
carry /= 2;
}
//千万别忘了
if(carry>0)
{
result[n] = '1';
result[n+1] = '\0';
}
else
result[n] = '\0';
reverse(result);
return result;
}