Go: package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"
)

var scanner = bufio.NewScanner(os.Stdin)

const INF = 0x7FFFFFFF

var pass [][]int

func main() {
	for scanner.Scan() {
		pass = make([][]int, 200)
		for i := range pass {
			pass[i] = make([]int, 200)
		}
		buf := strings.Split(scanner.Text(), " ")
		c, _ := strconv.Atoi(buf[0])
		n, _ := strconv.Atoi(buf[1])
		m, _ := strconv.Atoi(buf[2])
		s, _ := strconv.Atoi(buf[3])
		d, _ := strconv.Atoi(buf[4])
		if c == 0 && n == 0 && m == 0 && s == 0 && d == 0 {
			break
		}
		s--
		d--
		for i := 0; i < 200; i++ {
			for j := 0; j < 200; j++ {
				pass[i][j] = INF
			}
		}
		for i := 0; i < 200; i++ {
			pass[i][i] = 0
		}
		for i := 0; i < m; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			a, _ := strconv.Atoi(buf_[0])
			b, _ := strconv.Atoi(buf_[1])
			f, _ := strconv.Atoi(buf_[2])
			a--
			b--
			pass[a][b] = f
			pass[b][a] = f
		}
		fmt.Println(dijkstra(s, d, c, n))
	}
}

func dijkstra(s, g, c, n int) float64 {
	d := make([][]float64, 200)
	used := make([][]bool, 200)
	for i := 0; i < 200; i++ {
		d[i] = make([]float64, 20)
		used[i] = make([]bool, 20)
	}
	for i := range d {
		for j := range d[i] {
			d[i][j] = INF
		}
	}
	d[s][c] = 0
	for {
		v := -1
		w := -1
		for u := 0; u < n; u++ {
			for i := 0; i < c+1; i++ {
				if !used[u][i] && (v == -1 || d[u][i] < d[v][w]) {
					v = u
					w = i
				}
			}
		}
		if v == -1 {
			break
		}
		used[v][w] = true
		for u := 0; u < n; u++ {
			d[u][w] = math.Min(d[u][w], d[v][w]+float64(pass[v][u]))
			if w-1 >= 0 && pass[v][u] != INF {
				d[u][w-1] = math.Min(d[u][w-1], d[v][w]+(float64(pass[v][u]/2.0)))
			}
		}
	}
	ret := float64(INF)
	for i := 0; i < c+1; i++ {
		ret = math.Min(ret, d[g][i])
	}
	return ret
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<functional>

using namespace std;
typedef pair<int, int> Pi;
typedef pair<int, Pi> Ti;

int c, n, m, s, d;
vector<vector<Pi>> edge;

int djk(int s, int g) {
	int d[100 + 16][11];
	for (int i = 0; i < n; i++)for (int j = 0; j <= c; j++)d[i][j] = 1000000000;
	d[s][c] = 0;
	priority_queue<Ti, vector<Ti>, greater<Ti>> pq;
	pq.push(make_pair(0, make_pair(s, c)));
	while (pq.size()) {
		Ti tmp = pq.top(); pq.pop();
		int N = tmp.second.first, ticket = tmp.second.second;
		if (d[N][ticket] < tmp.first)continue;
		for (int i = 0; i < edge[N].size(); i++) {
			int to = edge[N][i].first, cost = edge[N][i].second;
			if (ticket > 0) {
				if (d[to][ticket - 1] > d[N][ticket] + cost / 2) {
					d[to][ticket - 1] = d[N][ticket] + cost / 2;
					pq.push(make_pair(d[to][ticket - 1], make_pair(to, ticket - 1)));
				}
			}
			if (d[to][ticket] > d[N][ticket] + cost) {
				d[to][ticket] = d[N][ticket] + cost;
				pq.push(make_pair(d[to][ticket], make_pair(to, ticket)));
			}
		}
	}
	int ans = 1000000000;
	for (int i = 0; i <= c; i++)ans = min(ans, d[g][i]);
	return ans;
}

int main() {
	while (cin >> c >> n >> m >> s >> d, c + n + m + s + d) {
		s--, d--;
		edge.resize(n);

		for (int i = 0; i < m; i++) {
			int a, b, f;
			cin >> a >> b >> f, a--, b--;
			edge[a].push_back(make_pair(b, f));
			edge[b].push_back(make_pair(a, f));
		}
		cout << djk(s, d) << endl;
		edge.clear();
	}
	return 0;
}

C++: #include<queue>
#include<cstdio>
#include<algorithm>

#define	mp	make_pair

using namespace std;

typedef	pair<int,int>	pii;

const int inf=1<<29;
int adj[100][100],memo[100][11];
bool visited[100][11];

int main(){
	for(int c,m,n,src,dst;scanf("%d%d%d%d%d",&c,&m,&n,&src,&dst),c;){
		src--,dst--;
		for(int i=0;i<n;i++)for(int j=0;j<n;j++)	adj[i][j]=(i==j?0:inf);
		for(int i=0;i<n;i++)for(int j=0;j<=c;j++)	memo[i][j]=inf,visited[i][j]=false;
		for(int i=0;i<m;i++){
			int a,b,fee;	scanf("%d%d%d",&a,&b,&fee);
			a--,b--;
			adj[a][b]=adj[b][a]=fee;
		}

		memo[src][0]=0;
		priority_queue< pair<int,pii> > pq;	pq.push(mp(0,mp(src,0)));
		while(!pq.empty()){
			pair<int,pii> a=pq.top();	pq.pop();
			int fee=-a.first;
			int u=a.second.first;
			int tic=a.second.second;
			if(u==dst)	break;

			if(visited[u][tic])	continue;
			visited[u][tic]=true;

			for(int v=0;v<n;v++){
				if(!visited[v][tic] && fee+adj[u][v]<memo[v][tic]){
					memo[v][tic]=fee+adj[u][v];
					pq.push(mp(-memo[v][tic],mp(v,tic)));
				}
				if(tic<c && !visited[v][tic+1] && fee+adj[u][v]/2<memo[v][tic+1]){
					memo[v][tic+1]=fee+adj[u][v]/2;
					pq.push(mp(-memo[v][tic+1],mp(v,tic+1)));
				}
			}
		}

		int feemin=inf;
		for(int i=0;i<=c;i++)	feemin=min(feemin,memo[dst][i]);
		printf("%d\n",feemin);
	}

	return 0;
}

C++: #include <iostream>
#include <queue>
#include <vector>
#include <functional>

using namespace std;

const int INF = 10000000;

int solve( int city[101][101], int s, int d, int c, int n ){
	int dist[11][101];
	int history[101];

	for( int i = 0;i < 11;i++ ){
		for( int j = 0;j < 101;j++ ){
			dist[i][j] = INF;
		}
	}

	for( int i = 0;i < 101;i++ ){
		history[i] = 0;
	}

	for( int i = 0;i < 11;i++ ) dist[i][s] = 0;

	typedef pair<int,int> data;
	typedef pair<int,data> graph;
	priority_queue<graph,vector<graph>,greater<graph> > q;

	q.push( graph( 0, data( s, c ) ) );

	while( !q.empty() ){
		graph a = q.top();
		int u = a.second.first;
		int uc = a.second.second;
		q.pop();
		history[u] = 1;

		for( int i = 1;i <= n;i++ ){
			if( city[u][i] == INF || history[i] ) continue;

			if( dist[uc][i] > dist[uc][u] + city[u][i] ){
				dist[uc][i] = dist[uc][u] + city[u][i];
				q.push( graph( dist[uc][i], data( i, uc ) ) );
			}

			if( uc && dist[uc - 1][i] > dist[uc][i] + city[u][i] / 2 ){
				dist[uc - 1][i] = dist[uc][u] + city[u][i] / 2;
				q.push( graph( dist[uc - 1][i], data( i, uc - 1 ) ) );
			}
		}
	}
	int answer = INF;
	for( int i = 0;i < 11;i++ ) answer = min( dist[i][d], answer );
	return answer;

}

int main(int argc, char const* argv[])
{
	int c,n,m,s,d;
	int city[101][101];

	while( cin >> c >> n >> m >> s >> d && c != 0 ){
		int a,b,f;
		for( int i = 0;i < 101;i++ ){
			for( int j = 0;j < 101;j++ ){
				city[i][j] = INF;
			}
		}
		for( int i = 0;i < m;i++ ){
			cin >> a >> b >> f;
			city[a][b] = f;
			city[b][a] = f;
		}

		cout << solve( city, s, d, c, n ) << endl;
	}

	return 0;
}

C++: #include<iostream>
#include<queue>
#include<vector>
using namespace std;
#define MAX 100000
#define MAX_NODE_ID 101
#define MAX_TICKET 11
class Node{
public:
	int id;
	int cost;
	int ticket;
	Node(int i,int c,int t){
		id=i;
		cost=c;
		ticket=t;
	}
	bool operator < (const Node &o) const{
		return cost > o.cost;
	}
};
typedef priority_queue<Node> PQ;
int table[MAX_NODE_ID][MAX_NODE_ID];
bool visited[MAX_NODE_ID][MAX_TICKET];
int main(){

	for(int c,n,m,s,d;cin>>c>>n>>m>>s>>d&&(c||n||m||s||d);){
		for(int i=0;i<MAX_NODE_ID;i++)for(int j=0;j<MAX_NODE_ID;j++)table[i][j]=MAX;
		for(int i=0;i<MAX_NODE_ID;i++)for(int j=0;j<MAX_TICKET;j++)visited[i][j]=false;
		for(int i=0,a,b,f;i<m&&cin>>a>>b>>f;i++){
			table[a][b]=f;
			table[b][a]=f;
//			cout<<"table["<<a<<"]["<<b<<"]"<<table[a][b]<<endl;
//			cout<<"table["<<b<<"]["<<a<<"]"<<table[b][a]<<endl;
		}
		PQ pq;
		Node start(s,0,c);
		pq.push(start);
		while(!pq.empty()){
			int current_node=pq.top().id;
			int current_cost=pq.top().cost;
			int current_ticket=pq.top().ticket;
//			cout<<"current:"<<current_node<<endl;
			if(current_node==d)break;
			if(visited[current_node][current_ticket]);
			else{
				for(int i=1;i<=n;i++){
					if(current_node==i)continue;
					if(table[current_node][i]==MAX)continue;
	//				cout<<"["<<current_node<<"]["<<i<<"]"<<"cost:"<<table[current_node][i]<<endl;
					Node node1(i,current_cost+table[current_node][i],current_ticket);
					pq.push(node1);
					visited[current_node][current_ticket]=true;
					if(current_ticket>0){
						Node node2(i,current_cost+(table[current_node][i]/2),current_ticket-1);
						pq.push(node2);
						visited[current_node][current_ticket-1]=true;
					}
				}
			}
			pq.pop();
		}
		cout<<pq.top().cost<<endl;
	}


	return 0;
}