HDU 3395 Special Fish

裸的KM吧。

#include <cstdio>
#include <vector>
#include <cstring>
#include <algorithm>
#define maxn 105
#define INF 1<<30
using namespace std;

struct KM{
    vector<int> G[maxn];
    int W[maxn][maxn],n;
    int Lx[maxn],Ly[maxn];
    int left[maxn];
    bool S[maxn],T[maxn];

    void init(int n)
    {
        this->n = n;
        for(int i = 0;i < n;i++)    G[i].clear();
        memset(W,0,sizeof(W));
    }

    void add_edge(int u,int v,int w)
    {
        G[u].push_back(v);
        W[u][v] = w;
    }

    bool match(int i)
    {
        S[i] = true;
        for(int k = 0;k < G[i].size();k++)
        {
            int j = G[i][k];
            if(Lx[i] + Ly[j] == W[i][j] && !T[j])
            {
                T[j] = true;
                if(left[j] == -1 || match(left[j]))
                {
                    left[j] = i;
                    return true;
                }
            }
        }
        return false;
    }
    void update()
    {
        int a = INF;
        for(int i = 0;i < n;i++)    if(S[i])
            for(int k = 0;k < G[i].size();k++)
            {
                int j = G[i][k];    if(!T[j])
                a = min(a,Lx[i] + Ly[j] - W[i][j]);
            }
        for(int i = 0;i < n;i++)
        {
            if(S[i])    Lx[i] -= a;
            if(T[i])    Ly[i] += a;
        }
    }

    void solve()
    {
        for(int i = 0;i < n;i++)
        {
            Lx[i] = *max_element(W[i],W[i]+n);
            left[i] = -1;
            Ly[i] = 0;
        }
        for(int i = 0;i < n;i++)
        {
            while(1)
            {
                for(int j = 0;j < n;j++)    S[j] = T[j] = 0;
                if(match(i))    break;
                else            update();
            }
        }
    }
};
KM solver;
int val[maxn];
int main(){
    int n;
    while(scanf("%d",&n),n){
        solver.init(n);
        for(int i = 0;i < n;i++)
            scanf("%d",&val[i]);
        char str[105];
        for(int i = 0;i < n;i++){
            scanf("%s",str);
            for(int j = 0;j < n;j++){
                if(str[j] == '1'){
                    solver.add_edge(i,j,val[i]^val[j]);
                }else{
                    solver.add_edge(i,j,0);
                }
            }
        }
        solver.solve();
        int ans = 0;
        for(int i = 0;i < n;i++){
            if(solver.left[i] != -1)
                ans += solver.W[solver.left[i]][i];
        }
        printf("%d
",ans);
    }
    return 0;
}