LeetCode 67 --- 二进制求和

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"

 

题解：

void reverse(char *a,int n)
{
    int i= 0;
    int j = n-1;
    char tmp;
    while(i<j)
    {
        tmp = a[i];
        a[i] = a[j];
        a[j] = tmp;
        i++;
        j--;
    }
}
 
char* addBinary(char* a, char* b)
{
    int m = strlen(a);
    int n = strlen(b);
    reverse(a,m);
    reverse(b,n);
 
    int maxn = (m > n ? m : n);
    char * ans = (char*) malloc(sizeof(char)*(maxn + 2));
    int c = 0;
    int i = 0;
    int j = 0;
    int k = 0;
 
    while(i<m && j<n)
    {
        int d = (a[i]-'0') +(b[j]-'0') + c;
        ans[k] = d%2 + '0';
        c = d/2;
        i++;
        j++;
        k++;
    }
 
    while(i<m)
    {
        int d = (a[i] - '0') +c;
        ans[k] = d%2 + '0';
        c =d/2;
        i++;
        k++;
    }
 
    while(j<n)
    {
        int d = (b[j]-'0')+c;
        ans[k] = d%2 +'0';
        c = d/2;
        j++;
        k++;
    }
 
    if(c==1)
    {
        ans[k] = '1';
        k++;
    }
 
    ans[k] = '\0';
    reverse(ans,k);
    return ans;
}