Add Binary

https://leetcode.com/problems/add-binary/

Given two binary strings, return their sum (also a binary string).

For example,
a = “11”
b = “1”
Return “100”.

计算过程类似Verilog的全加器。

char* addBinary(char* a, char* b) {    int i;    int l1, l2, l3, temp;    l1 = strlen(a);    l2 = strlen(b);    l3 = l1 > l2 ? l1 + 2 : l2 + 2;    temp = l3;    char *result = (char *)malloc(l3 * sizeof(char));    int t1, t2;    int sum, cout = 0;    cout = 0;    l1--;    l2--;    l3--;    result[l3] = '\0';    while (l1 >= 0 || l2 >= 0) {        t1 = l1 >= 0 ? a[l1] - '0' : 0;        t2 = l2 >= 0 ? b[l2] - '0' : 0;        sum = t1 ^ t2 ^ cout;        cout = (t1 & t2) | (t1 & cout) | (t2 && cout);        result[--l3] = sum + '0';        l1--;        l2--;    }    if (cout == 1)        result[--l3] = '1';    else {        for(int i = 1; i < temp; i++) {            result[i-1] = result[i];  // move left        }    }    return result;}