hdu Integer Inquiry 解题报告

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1047

题目意思：就是求大整数加法。有多个案例，每个案例之间要输出一个空格。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

const int maxn = 10000 + 10;
char t[maxn];
int s[maxn], ans[maxn];

int main()
{
    int l1, l2, n, i, j, l, len, num;
    scanf("%d", &n);
    while (n--)
    {
        num = 0;
        memset(ans, 0, sizeof(ans));
        while (cin >> t && strcmp(t, "0"))
        {
            memset(s, 0, sizeof(s));
            l1 = strlen(t);
            for (i = 0; i < l1; i++)
                s[i] = t[l1-i-1] - '0';
            num++;
            if (num == 1)
            {
                for (i = 0; i < l1; i++)
                    ans[i] = s[i];
                l2 = l1;
            }
            else
            {
                len = max(l1, l2);  // l1:s[i] l2:ans[i]
                l = min(l1, l2);
                int sum, c = 0;
                for (i = 0; i < len; i++)
                {
                    if (i < l)
                    {
                        sum = s[i] + ans[i] + c;
                        ans[i] = sum % 10;
                        c = (sum > 9 ?  1 : 0);
                    }
                    else
                    {
                        if (l1 == len)
                            sum = s[i] + c;
                        else
                            sum  = ans[i] + c;
                        ans[i] = sum % 10;
                        c = (sum > 9 ?  1 : 0);
                    }
                }
                if (c == 1 && i == len)
                {
                    ans[len] = 1;
                    l2 = len + 1;
                }
                else
                    l2 = len;   // 关键之处！！！！之前不记得更新错了好多次！！！
            }
        }
        if (!num)
            printf("0");
        else
        {
            for (i = maxn-1; i >= 0; i--)
            {
                if (ans[i])
                    break;
            }
            for ( ; i >= 0; i--)
                printf("%d", ans[i]);
        }
        printf("
");
        if (n)
            cout << endl;
    }
    return 0;
}

　　忽略格式问题，借鉴了别人的写法

   

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

const int maxn = 1e5 + 10;
char t[maxn];
int num[maxn];

void add(char s[])
{
    int z = 0;
    int len = strlen(s);
    for (int i = len-1; i >= 0; i--)
    {
        num[z] += (s[i] - '0');
        num[z+1] += num[z] / 10;
        num[z] %= 10;
        z++;
    }
}

int main()
{
    int i, ok = 0;
    memset(num, 0, sizeof(num));
    while (scanf("%s", t) != EOF && strcmp(t, "0"))
        add(t);
    for (i = maxn; i >= 0; i--)
    {
        if (num[i])
        {
            ok = 1;
            break;
        }
    }
    for ( ; i >= 0 && ok; i--)
         printf("%d", num[i]);
    if (!ok)
        printf("0");
    printf("
");
    return 0;
}