HDU 1511（Increasing Sequences）

#include <cstdio>
#include <cstring>
const int MAXN = 85;

char num[85];
int dp[85];
int n;

//判断num数组中，从pos1起始，长为len1的数，是否小于，从pos2开始，长为len2的数
bool judge(int pos1, int len1, int pos2, int len2)
{
    while (num[pos1] == '0' && len1 > 0) //去除前导0
    {
        ++pos1;
        --len1;
    } 
    while (num[pos2] == '0' && len2 > 0) //去除前导0
    {
        ++pos2;
        --len2;
    }
    if (len1 < len2)
        return true;
    else if (len1 > len2)
        return false;
    else
    {
        for (int i = 0; i < len1; i++)
        {
            if (num[pos1 + i] < num[pos2 + i])
                return true;
            if (num[pos1 + i] > num[pos2 + i])
                return false;
        }
    }
    return false;
}

//输出
void output(int pos)
{
    if (pos > n) 
        return;
    if (pos != 1) 
        printf(",");
    for (int i = pos; i < pos + dp[pos]; i++)
        printf("%c", num[i]);
    output(pos + dp[pos]);
}

int main()
{
    while (scanf("%s", num + 1))
    {
        if (strcmp(num + 1, "0") == 0)
            break;

        n = strlen(num + 1);
        //第一次动态规划，从前向后，找出最小的最后一个数
        dp[1] = 1;
        for (int i = 2; i <= n; i++)
        {
            dp[i] = i;
            for (int j = i - 1; j >= 1; j--)
            {
                if (judge(j - dp[j] + 1, dp[j], j + 1, i - j))
                {
                    dp[i] = i - j;
                    break;
                }
            }
        }
        //第二次动态规划，从后向前，找出最大的第一个数
        int pos = n - dp[n] + 1;
        dp[pos] = dp[n];
        for (int i = pos - 1; i >= 1; i--)
        {
            if (num[i] == '0')
            {
                dp[i] = dp[i + 1] + 1;
                continue;
            }
            for (int j = pos; j > i; j--)
            {
                if (judge(i, j - i, j, dp[j]))
                {
                    dp[i] = j - i;
                    break;
                }
            }  
        }

        output(1);
        printf("\n");
    }
    return 0;
}