UVA 11045 My T-shirt suits me

一开始就想到网络流。。后来一想暴力能不能过。自己写的T了。看了别人有暴力过的。

暴力的思路就是6进制数字表示给予的衣服的数量。然后每个人的需求表示成01 的6位串然后爆搜。

网络流就建一个源一个汇 然后针对输入 i  - i + 6 边权为N/6； 然后M个人由衣服连M个人边权为1。与源直接相连的点就INF求最大流值判断即可。

别人的建图更简单一些。不需要设置INF；思路一样

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
int src,tag;
int N,M;
const int INF = 0x3f3f3f3f ;
char size[10][20] = {"xxa","XXL","XL","L","M","S","XS"};
int d[100],cap[100][100];
bool inq[100];
int flow[100][100];
int p[100];
void read()
{
    scanf("%d%d",&N,&M);
    N /= 6;
    memset(cap,0,sizeof(cap));
    for (int i = 1; i <= 6; i++)  { cap[0][i] = INF; cap[i][i + 6] = N; }
    for (int j = 1; j <= M; j++)
    {
        char a[8],b[8];
        scanf("%s%s",a,b);
        int s1 = -1, s2;
        for (int i = 1; i <= 6; i++)
        {
            if (strcmp(size[i],a) == 0)
                 s1 = i;
            if (strcmp(size[i],b) == 0)
                 s2 = i;
        }
        //printf("%d %d\n",s1,s2);
        cap[s1 + 6][12 + j] = 1;
        cap[s2 + 6][12 + j] = 1;
        cap[12 + j][12 + M + 1] = 1;
    }
    src = 0;
    tag = 12 + M + 1;
}
int Edmons_karp()
{
    queue<int>q;
    int a[100];
    while (!q.empty()) q.pop();
    memset(flow,0,sizeof(flow));
    int ans = 0;
    while (true)
    {
        memset(a,0,sizeof(a));
        a[src] = INF;
        q.push(src);
        while(!q.empty())
        {
            int u = q.front(); q.pop();
            for (int v = 1; v <= tag; v++)
                if (!a[v] && cap[u][v] > flow[u][v])
            {
                p[v] = u;
                q.push(v);
                a[v] = min(a[u],cap[u][v] - flow[u][v]);
            }
        }
        if (a[tag] == 0) break;
        for (int u = tag; u != src; u = p[u])
        {
            flow[p[u]][u] += a[tag];
            flow[u][p[u]] -= a[tag];
        }
        ans += a[tag];
    }
    return ans;
}
int main()
{
    //freopen("sample.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while (T--)
    {
        read();
        int ans = Edmons_karp();
        //printf("%d\n",ans);
        if (ans >= M) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}

TLE 的代码也贴一下吧

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
int st[32];
int N,M;
bool found;
char size[10][20] = {"XXL","XL","L","M","S","XS"};
int res;
void read()
{
    res = 0;
    scanf("%d%d",&N,&M);
    N /= 6;
    char tmp[10];
    for (int i = 0; i < 6 ; i++)
        tmp[i] = N + ‘0‘;
    tmp[6] = ‘\0‘;
    sscanf(tmp,"%d",&res);
    memset(st,0,sizeof(st));
    for (int i = 1; i <= M; i++)
    {
        char a[6],b[6];
        scanf("%s%s",a,b);
        int j;
        for (j = 0; j < 6; j++) if (strcmp(a,size[j]) == 0) break;
        st[i] |= 1 << j;
        for (j = 0; j < 6; j++) if (strcmp(b,size[j]) == 0) break;
        st[i] |= 1 << j;
    }
}
void calcu(int cur, int sta, int cnt)
{
    if (found) return ;
    if (cnt >= M) { found = true; return ; }
    int temp = sta;
    bool change = false;
    char str[20];
    for (int i = cur; i <= M; i++)
    {
        int a = -1,b = -1;
        for (int j = 0; j < 6; j++)
        {
            if (st[i] & (1 << j))
            {
                if (a == -1)
                {
                    a = j;
                }
                else
                    b = j;
            }
        }
        sprintf(str,"%d",temp);
        if (str[a] - ‘0‘ > 0)
        {
            change = true;
            str[a]--;
            sscanf(str,"%d",&temp);
            calcu(cur + 1, temp, cnt + 1);
            str[a]++;
        }
        temp = sta;
        if (str[b] - ‘0‘ > 0)
        {
            change = true;
            str[b]--;
            sscanf(str,"%d",&temp);
            calcu(cur + 1, temp, cnt + 1);
            str[b]++;
        }
        if (!change) return ;
    }
}
int main()
{
    //freopen("sample.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while (T--)
    {
        found = false;
        read();
        calcu(1,res,0);
        if (found) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}