一本通1627：【例 3】最大公约数

#include <bits/stdc++.h>
using namespace std;
int a[2000], b[2000], maxnum = 1e8;
void jtll(int tmp[]) {
    string s;
    cin >> s;
    int len = s.length(), cnt = 0, ans = 0, t = 1, y = 1;

    for (int i = len - 1; i >= 0; i--) {
        cnt++;
        ans += t * (s[i] - 48);
        t *= 10;

        if (cnt == 8) {
            tmp[y++] = ans;
            ans = 0;
            cnt = 0;
            t = 1;
        }
    }

    if (cnt > 0)
        tmp[y] = ans;

    tmp[0] = (len + 7) / 8;
}
bool dlb() {
    if (a[0] > b[0])
        return true;

    if (a[0] < b[0])
        return false;

    for (int i = a[0]; i > 0; i--)
        if (a[i] > b[i])
            return true;
        else if (a[i] < b[i])
            return false;

    return true;
}
void SB(int a[], int b[]) {
    for (int i = 1; i <= a[0]; i++) {
        a[i] -= b[i];

        if (a[i] < 0)
            a[i] += maxnum, a[i + 1]--;
    }

    while (a[a[0]] == 0 and a[0] > 0)
        a[0]--;
}
void jntm(int a[]) {
    for (int i = a[0]; i >= 1; i--) {
        a[i - 1] += (a[i] % 2) * maxnum;
        a[i] /= 2;
    }

    while (a[a[0]] == 0 and a[0] > 0)
        a[0]--;
}
void muti(int a[], int m) {
    int g = 0;

    for (int i = 1; i <= a[0]; i++) {
        int x = a[i] * m + g;
        a[i] = x % maxnum;
        g = x / maxnum;

        if (i == a[0] and g > 0)
            a[0]++;
    }
}
void print(int a[]) {
    for (int i = a[0]; i > 0; i--)
        if (i == a[0])
            cout << a[i];
        else
            cout << setw(8) << setfill('0') << a[i];
}
int main() {
    jtll(a);
    jtll(b);
    int timer = 1;

    while (true) {
        if (a[1] % 2 == 0 and b[1] % 2 == 0) {
            jntm(a);
            jntm(b);
            timer *= 2;
            continue;
        } else if (a[1] % 2 == 0) {
            jntm(a);
            continue;
        } else if (b[1] % 2 == 0) {
            jntm(b);
            continue;
        }

        if (dlb()) {
            SB(a, b);

            if (a[0] == 0) {
                muti(b, timer);
                print(b);
                break;
            }
        } else {
            SB(b, a);

            if (b[0] == 0) {
                muti(a, timer);
                print(a);
                break;
            }
        }
    }

    return 0;
}