Roads

原题

磨了三天，终于ＡＣ了，开始时照着书上写，心里很没底，发现如果有错，很难改，后来又到网上找代码，又看不懂。

最后下定决心自己写。思路参照２００５年国家集训队王俊的论文。

#include <iostream>#include <algorithm>#define MAXN 70//数组开小了还WA了一次#define MAXE 420#define INF (1 << 28)using namespace std ;int num[MAXN][MAXN] , gg[MAXN][MAXN] , pre[MAXN] , n , m , depth[MAXN] , size ,lx[MAXE] , ly[MAXE] , x[MAXE] , y[MAXE] , g[MAXE][MAXE] , link[MAXE] ;bool l[MAXE] , r[MAXE] ;void DFS (int i , int d){for (int j = 1 ; j <= n ; j ++)if (num[i][j] && !pre[j]){pre[j] = i ;depth[j] = d ;DFS (j , d + 1) ;}}int LCA (int a , int b){int h1 , h2 ;h1 = depth[a] , h2 = depth[b] ;while (h1 > h2)h1 -- , a = pre[a] ;while (h2 > h1)h2 -- , b = pre[b] ;while (a != b)a = pre[a] , b = pre[b] ;return a ;}void BuildGraph (int k , int u , int v , int w){int i , par ;par = LCA (u , v) ;for (i = u ; i != par ; i = pre[i])if (gg[i][pre[i]] > w)g[num[i][pre[i]]][k] = gg[i][pre[i]] - w ;for (i = v ; i != par ; i = pre[i])if (gg[i][pre[i]] > w)g[num[i][pre[i]]][k] = gg[i][pre[i]] - w ;}void Readin (){int i , u , v ,w ;scanf ("%d%d" , &n , &m) ;size = max (n - 1 , m - n + 1) ;memset (num , 0 , sizeof (num)) ;memset (gg , 0 , sizeof (gg)) ;memset (g , 0 , sizeof (g)) ;memset (pre , 0 , sizeof (pre)) ;memset (link , -1 , sizeof (link)) ;memset (x , 0 , sizeof (x)) , memset (y , 0 , sizeof (y)) ;for (i = 1 ; i < n ; i ++){scanf ("%d%d%d" , &u , &v , &w) ;gg[u][v] = gg[v][u] = x[i] = w ;num[u][v] = num[v][u] = i ;//记录边的序号}pre[1] = -1 , depth[1] = 0 ;DFS (1 , 1) ;for (i = 1 ; i <= m - n + 1 ; i ++){scanf ("%d%d%d" , &u , &v , &w) ;y[i] = w ;BuildGraph (i , u , v , w) ;}}bool Find (int i){l[i] = true ;for (int j = 1 ; j <= size ; j ++)if (!r[j] && lx[i] + ly[j] == g[i][j]){r[j] = true ;if (link[j] == -1 || Find (link[j])){link[j] = i ;return true ;}}return false ;}void Adjust (){int i , j , d = INF ;for (i = 1 ; i <= size ; i ++)if (l[i]){for (j = 1 ; j <= size ; j ++)if (!r[j])d = min (d , lx[i] + ly[j] - g[i][j]) ;}for (i = 1 ; i <= size ; i ++){if (l[i])lx[i] -= d ;if (r[i])ly[i] += d ;}}void KM (){int i , j ;memset (lx , 0 , sizeof (lx)) ;memset (ly , 0 , sizeof (ly)) ;for (i = 1 ; i <= size ; i ++)for (j = 1 ; j <= size ; j ++)lx[i] = max (lx[i] , g[i][j]) ;for (i = 1 ; i <= size ; i ++){memset (l , false , sizeof (l)) ;memset (r , false , sizeof (r)) ;while (!Find (i)){Adjust () ;memset (l , false , sizeof (l)) ;memset (r , false , sizeof (r)) ;}}}void Print (){int i ;for (i = 1 ; i <= size ; i ++)x[link[i]] -= lx[link[i]] , y[i] += ly[i] ;for (i = 1 ; i < n ; i ++)printf ("%d/n" , x[i]) ;for (i = 1 ; i <= m - n + 1 ; i ++)printf ("%d/n" , y[i]) ;}int main (){Readin () ;KM () ;Print () ;return 0 ;}