题目看着向生成树,但实际上是最短路径+堆优化。
#include <stdio.h>
const int LEN = 50005; const __int64 MAX = 0x7fffffffffffffff;
struct HEAD { int next; int last; __int64 dis; int used; }head[LEN];
struct NODE { int num; __int64 len; int next; }node[LEN*2]; int next;
//堆部分 int hash[LEN]; //堆中部分现在所在的位置 struct HEAP { int num; //指向堆外面 __int64 dis; }heap[LEN]; int hlen; //堆大小
__int64 weight[LEN]; //记录重量
inline void init ( int v ) {
hlen = 0; next = 0; for ( int i=0; i<v; i++ ) { head[i].dis = MAX; head[i].next = -1; head[i].used = 0; } }
void ins ( int a, int b, __int64 len ) {
node[next].num = b; node[next].next = -1; node[next].len = len; next ++;
if ( head[a].next==-1 ) head[a].next = next-1; else node[ head[a].last ].next = next-1; head[a].last = next-1; }
inline void swap ( int a, int b ) {
struct { __int64 dis; int num; }temp;
temp.dis = heap[a].dis; temp.num = heap[a].num; heap[a].dis = heap[b].dis; heap[a].num = heap[b].num; heap[b].dis = temp.dis; heap[b].num = temp.num; }
inline void moveup ( int p ) {
while ( p>0&&heap[(p-1)/2].dis>heap[p].dis ) { hash[ heap[p].num ] = (p-1)/2; hash[ heap[ (p-1)/2 ].num ] = p; swap ( p, (p-1)/2 ); p = (p-1)/2; } }
inline void movedown ( int p ) {
int flag = 1; while ( p<hlen&&flag ) { int lson = p*2+1; int rson = p*2+2; flag = 0; if ( rson<hlen ) { if ( heap[lson].dis<=heap[rson].dis&&heap[lson].dis<heap[p].dis ) { hash[ heap[p].num] = lson; hash[ heap[lson].num] = p; swap ( p, lson ); p = lson; flag = 1; } else if ( heap[rson].dis<=heap[lson].dis&&heap[rson].dis<heap[p].dis ) { hash[ heap[p].num] = rson; hash[ heap[rson].num] = p; swap ( p, rson ); p = rson; flag = 1; } } else if ( lson<hlen ) { if ( heap[lson].dis<heap[p].dis ) { hash[ heap[p].num] = lson; hash[ heap[lson].num] = p; swap ( p, lson ); p = lson; flag = 1; } } } }
void dj ( int s, int n ) {
head[s].dis = 0; for ( int i=0; i<n; i++ ) { heap[hlen].dis = head[i].dis; heap[hlen].num = i; hlen ++; hash[i] = hlen-1; moveup ( hlen-1 ); } for ( int i=0; i<n-1; i++ ) { __int64 min0; int min1; min0 = heap[0].dis; min1 = heap[0].num; if ( min0==MAX ) return; head[min1].used = 1; int tmp = heap[hlen-1].num; hash[tmp] = 0; hash[min1] = hlen-1; swap ( 0, hlen-1 ); hlen--; moveup ( hash[tmp] ); movedown ( hash[tmp] ); for ( int j=head[min1].next; j!=-1; j=node[j].next ) { int e = node[j].num; __int64 t_dis = head[min1].dis+node[j].len; if ( t_dis<head[e].dis ) { head[e].dis = t_dis; heap[hash[e]].dis = t_dis; moveup ( hash[e] ); } } } }
int main () {
int t; scanf ( "%d", &t ); while ( t-- ) { int v, e; scanf ( "%d%d", &v, &e ); for ( int i=0; i<v; i++ ) scanf ( "%I64d", &weight[i] ); init ( v ); for ( int i=0; i<e; i++ ) { int a, b; __int64 len; scanf ( "%d%d%I64d", &a, &b, &len ); if ( a!=b ) { ins ( a-1, b-1, len ); ins ( b-1, a-1, len ); } }
dj ( 0, v ); __int64 ans = 0; for ( int i=0; i<v; i++ ) { if ( head[i].dis==MAX ) { ans = -1; break; } ans += head[i].dis*weight[i]; } if ( ans==-1 ) printf ( "No Answer\n" ); else printf ( "%I64d\n", ans ); } return 0; }
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