最小生成树。地址: http://acm.pku.edu.cn/JudgeOnline/problem?id=1251
#include <stdio.h>
#include <stdlib.h>
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
const int LEN = 1000;
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
typedef struct
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
int b;
int e;
int length;
}type;
type seg[LEN];
int next;
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
void init ()
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
next = 0;
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
int point[LEN];
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
void make ( int n )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
for ( int i=0; i<n; i++ )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
point[i] = -1;
}
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
int find ( int a )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
if ( point[a] < 0 )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
return a;
}
int r = find ( point[a] );
point[a] = r;
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
return r;
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
void un ( int a, int b )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
int ra = find ( a );
int rb = find ( b );
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
if ( point[ra] < point[rb] )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
point[ra] += point[rb];
point[rb] = ra;
}
else
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
point[rb] += point[ra];
point[ra] = rb;
}
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
int cmp ( const void *a, const void *b )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
return ( ( type * )a )->length - ( ( type * )b )->length;
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
int kul ( int n )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
int ans = 0;
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
qsort ( seg, next, sizeof ( type ), cmp );
make ( n );
for ( int i=0; i< next; i++ )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
if ( find ( seg[i].b ) != find ( seg[i].e ) )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
ans += seg[i].length;
un ( seg[i].b, seg[i].e );
}
}
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
return ans;
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
int main ()
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedBlockStart.gif) ![](http://www.cppblog.com/Images/OutliningIndicators/ContractedBlock.gif) {
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
int n;
char chi[5], chj[5];
int len;
int in;
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
while ( scanf ( "%d", &n ) != EOF && n )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
init ();
for ( int i=0; i<n-1; i++ )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
scanf ( "%s%d", &chi, &len );
for ( int j=0; j<len; j++ )
![](http://www.cppblog.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif) {
scanf ( "%s%d", &chj, &in );
seg[next].b = chi[0] - 'A';
seg[next].e = chj[0] - 'A';
seg[next++].length = in;
}
}
![](http://www.cppblog.com/Images/OutliningIndicators/InBlock.gif)
printf ( "%d\n", kul ( n ) );
}
return 0;
}
![](http://www.cppblog.com/Images/OutliningIndicators/None.gif)
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