HDU 2255

Kuhn - Munkres 算法，第一次拍各种问题，不过还是A掉了。。

/*
ID:esxgx1
LANG:C++
PROG:hdu2255
*/
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

typedef long long LL;

#define LXN        307
#define RXN        307


int w[LXN][RXN];

int lx[LXN], ly[RXN];
char visx[LXN], visy[RXN];
int matched[RXN], slack[RXN];

int N;

#define LN        N
#define RN        N

int aug(int i)
{
    visx[i] = 1;
    for(int j=0; j<RN; ++j) {
        if (!visy[j]) {
            int d = lx[i] + ly[j] - w[i][j];
            if (!d) {
                visy[j] = 1;
                if (matched[j] < 0 || aug(matched[j])) {
                    matched[j] = i;
                    return 1;
                }
            } else if (slack[j] > d) slack[j] = d;
        }
    }
    return 0;
}

#define INF        0x3f3f3f3f

void work(void)
{
    for(int i=0; i<LN; ++i) {
        lx[i] = w[i][0];
        for(int j = 1; j<RN; ++j)
            if (w[i][j] > lx[i]) lx[i] = w[i][j];
    }
    for(int i=0; i<RN; ++i) ly[i] = 0;

    memset(matched, -1, sizeof(matched));

    // Kuhn-Munkres
    for(int i=0; i<LN; ++i) {
        for (int j=0; j<RN; ++j)
            slack[j] = INF;

        while(1) {
            memset(visx, 0, sizeof(visx));
            memset(visy, 0, sizeof(visy));
            if (aug(i)) break;

            int d, j = 0;
            for(; j<RN; ++j) if (!visy[j]) {d = j; break;}
            for(; j<RN; ++j)
                if (!visy[j] && slack[d] > slack[j])
                    d = j;
            d = slack[d];

            for(int j=0; j<LN; ++j)    if (visx[j]) lx[j] -= d;

            for(int j=0; j<RN; ++j)
                if (visy[j]) ly[j] += d;
                else slack[j] -= d;
        }
    }
}

// x (- [a, b] 优化
#define within(x, a, b)        ((unsigned)((x) - (a)) <= ((b) - (a)))

// 读入一个整数[返回值同scanf]
int readint(int *p)
{
    int ch;

    while(!within(ch=getchar(), '0', '9'))
        if(ch == EOF) return EOF;

    int rslt = 0;
    do
        rslt = rslt * 10 + (ch - '0');
    while(within(ch=getchar(), '0', '9'));
    *p = rslt;
    return 1;
}

int println_int(int i)
{
    char s[107], p = 0;
    while(i) {
        s[p++] = i % 10;
        i/=10;
    }
    while(p) putchar('0' + s[--p]);
    putchar('
');
}

int main(void)
{
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    #endif

    while(readint(&N) > 0) {
        for(int i=0; i<N; ++i)            // 第i个村子
            for(int j=0; j<N; ++j)
                 readint(&w[i][j]);

        work();

        int z = 0;
        for(int j=0; j<RN; ++j)
            if (matched[j] >= 0) z += w[matched[j]][j];
        println_int(z);
    }
    return 0;
}

014-09-18 21:44:16

Accepted

2255

234MS

656K

2298 B

G++