贪心 UVALive 6832 Bit String Reordering

 

题目传送门

/*
    贪心：按照0或1开头，若不符合，选择后面最近的进行交换。然后选取最少的交换次数
*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <map>
#include <queue>
using namespace std;

const int MAXN = 22 + 10;
const int INF = 0x3f3f3f3f;
int a[MAXN], b[MAXN], c[MAXN];

int main(void)        //UVALive 6832 Bit String Reordering
{
//    freopen ("A.in", "r", stdin);

    int n, m;
    while (scanf ("%d%d", &n, &m) == 2)
    {
        for (int i=1; i<=n; ++i)    {scanf ("%d", &a[i]);    c[i] = a[i];}
        for (int i=1; i<=m; ++i)    scanf ("%d", &b[i]);

        int cnt1 = 0, cnt2 = 0;    int now = 0;    int p = 0;
        bool ok1 = true, ok2 = true;
        for (int i=1; i<=m && ok1; ++i)
        {
            for (int j=1; j<=b[i]; ++j)
            {
                if (a[p+j] != now)
                {
                    int k = p + j;
                    while (k <= n && a[k] != now)    k++;
                    if (k == n+1 || a[k] != now)    {ok1 = false;    break;}
                    cnt1 += k - (p + j);
                    swap (a[k], a[p+j]);
                }
            }
            p += b[i];    now = 1 - now;
        }

        now = 1;    p = 0;
        for (int i=1; i<=m && ok2; ++i)
        {
            for (int j=1; j<=b[i]; ++j)
            {
                if (c[p+j] != now)
                {
                    int k = p + j;
                    while (k <= n && c[k] != now)    k++;
                    if (k == n+1 || c[k] != now)    {ok2 = false;    break;}
                    cnt2 += k - (p + j);
                    swap (c[p+j], c[k]);
                }
            }
            p += b[i];    now = 1 - now;
        }

//        printf ("%d %d\n", cnt1, cnt2);
        if (!ok1)    printf ("%d\n", cnt2);
        else if (!ok2)    printf ("%d\n", cnt1);
        else    printf ("%d\n", min (cnt1, cnt2));
    }

    return 0;
}