FZU 1912 Divisibility by Thirty-six（整除问题+字符串维护+贪心）

这个整除36的与整除45的完全一样,就是被4整除的有点多,但都是两位数,所以枚举后面两位就可以了.

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1005;
const int M = 15;
const int dir[30][2] = { {0, 0}, {4, 0}, {8, 0}, {1, 2}, {1, 6}, {2, 0}, {2, 4}, {2, 8}, {3, 2}, {3, 6}, {4, 4}, {8, 4}, {5, 2}, {5, 6}, {6, 0},

    {6, 4}, {6, 8}, {7, 2}, {7, 6}, {8, 8}, {9, 2}, {9, 6}
};

int tmp, rec[M], cnt[M];
int n, s[N], x, id;
bool flag;
char ans[N];

void init()
{
    char num[N];
    scanf("%s", num);
    x = strlen(num), tmp = 0;

    flag = false;
    memset(rec, 0, sizeof(rec));
    memset(ans, 0, sizeof(ans));

    for (int i = 0; i < x; i++)
    {
        int cur = num[i] - '0';
        tmp += cur;
        rec[cur]++;
    }
}
void put(int a[], int d, char *str)
{
    int len = 0;
    for (int i = 9; i >= 0; i--)
    {
        for (int j = 0; j < a[i]; j++)
            str[len++] = i + '0';
    }
    for (int i = 0; i < 2; i++)
        str[len++] = dir[d][i] + '0';
    str[len] = '';
}

bool cmp(char *a, char *b)
{
    for (int i = 0; a[i]; i++)
    {
        if (a[i] != b[i]) return a[i] < b[i];
    }
    return false;
}

void judge(int m)
{

    char now[N];
    put(cnt, id, now);
    if (m < x || (cmp(ans, now) && m == x))
    {
        flag = true;
        x = m;
        strcpy(ans, now);
    }
}

void dfs(int m, int d, int sum)
{

    if (d >= m)
    {
        if ((sum - tmp) % 9 == 0)    judge(m);
        return;
    }

    for (int i = 1; i <= 8; i++)
    {
        if (!cnt[i]) continue;
        cnt[i]--;
        dfs(m, d + 1, sum + i);
        cnt[i]++;
    }
}

void search(int d)
{
    for (int i = 0; i < 2; i++)
    {
        cnt[dir[d][i]]--;
        if (cnt[dir[d][i]] < 0) return;
    }
    id = d;
    for (int i = 0; i <= tmp && i <= x; i++)
        dfs(i, 0, 0);
}

bool isOK(char *str)
{
    int sum = 0, len = strlen(str);
    if (len == 0 && rec[0] == 0) return false;
    for (int i = 0; i < len; i++)
        sum += str[i] - '0';
    return !sum;
}

void solve()
{

    for (int i = 0; i < 22; i++)
    {
        memcpy(cnt, rec, sizeof(rec));
        search(i);
    }
    if (isOK(ans)) printf("0
");
    else if (flag) puts(ans);
    else printf("impossible
");
}

int main()
{
    int cas;
    scanf("%d", &cas);
    for (int i = 1; i <= cas; i++)
    {

        init();
        printf("Case %d: ", i);
        solve();
    }
    return 0;
}