1#include <stdio.h>
2#include <stdlib.h>
3#include <string.h>
4
5int gcd(int a, int b) {
6    while (b != 0) {
7        int t = b;
8        b = a % b;
9        a = t;
10    }
11    return a;
12}
13
14int lcm(int a, int b) {
15    return (a / gcd(a, b)) * b;
16}
17
18char* fractionAddition(char* expression) {
19    int numerator = 0, denominator = 1, n, d;
20    char sign, *ptr = expression;
21    while (*ptr) {
22        n = (*ptr == '-' || *ptr == '+') ? atoi(ptr) : 1;
23        sign = (*ptr == '-') ? '-' : '+';
24        ptr += (n == 1 ? 0 : (sign == '-' ? 1 : 2));
25        d = atoi(strchr(ptr, '/') + 1);
26        ptr = strchr(ptr, '/') + 1;
27        ptr += (*ptr == '-') ? 1 : 0;
28        
29        int commonDen = lcm(denominator, d);
30        numerator = numerator * (commonDen / denominator) + n * (commonDen / d);
31        denominator = commonDen;
32    }
33
34    int commonDiv = gcd(abs(numerator), denominator);
35    numerator /= commonDiv;
36    denominator /= commonDiv;
37
38    char *result = (char *)malloc(32);
39    sprintf(result, "%d/%d", numerator, denominator);
40    return result;
41}

1
public class Solution {
    public string FractionAdditionConsec(string expression) {
        int num = 0, den = 1, n, d;
        int i = 0, sign = 1;

        while (i < expression.Length) {
            if (expression[i] == '+' || expression[i] == '-') {
                sign = (expression[i] == '-') ? -1 : 1;
                i++;
            }

            int numBegin = i;
            while (expression[i] != '/') i++;
            n = int.Parse(expression.Substring(numBegin, i - numBegin));
            n *= sign;
            i++;

            int dBegin = i;
            while (i < expression.Length && Expression[i] >= '0' && expression[i] <= '9') i++;
            d = int.Parse(expression.Substring(dBegin, i - dBegin));

            int lcmDenom = den * (d / GCD(den, d));
            num = num * (lcmDenom / den) + n * (lcmDenom / d);
            den = lcmDenom;
        }

        int gcd = GCD(Math.Abs(num), den);
        return (num / gcd) + "/" + (den / gcd);
    }

    private int GCD(int a, int b) {
        return b == 0 ? a : GCD(b, a % b);
    }
}