126. Add Signed and Unsigned Integers Safely

#include <stdio.h>
#include <stdint.h>

int16_t signed_unsigned_sum(int8_t a, uint8_t b) {
    // Your logic here
    uint16_t x = (uint16_t)a;
    uint16_t y = (uint16_t)b;
    while(y){
        uint16_t sum = x^y;
        uint16_t carry = x & y;
        y = carry<<1;
        x = sum;
    }
    return (int16_t)x;
}

int main() {
    int8_t a;
    uint8_t b;
    scanf("%hhd %hhu", &a, &b);
    printf("%d", signed_unsigned_sum(a, b));
    return 0;
}