REVAMP - Revamping Trails

Tác giả: hieult

Ngôn ngữ: C++

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <ctime>
#include <deque>
#include <bitset>
#include <cctype>
#include <utility>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned int ui;
typedef unsigned long long ull;

#define Rep(i,n) for(int i = 0; i < (n); ++i)
#define Repd(i,n) for(int i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(int i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(int i = (a); i >= (b); --i)
#define Fit(i,v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
#define Fitd(i,v) for(__typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))

template<class F, class T> T convert(F a, int p = -1) {
    stringstream ss;
    if (p >= 0)
        ss << fixed << setprecision(p);
    ss << a;
    T r;
    ss >> r;
    return r;
}
template<class T> T gcd(T a, T b) {
    T r;
    while (b != 0) {
        r = a % b;
        a = b;
        b = r;
    }
    return a;
}
template<class T> T lcm(T a, T b) {
    return a / gcd(a, b) * b;
}
template<class T> T sqr(T x) {
    return x * x;
}
template<class T> T cube(T x) {
    return x * x * x;
}
template<class T> int getbit(T s, int i) {
    return (s >> i) & 1;
}
template<class T> T onbit(T s, int i) {
    return s | (T(1) << i);
}
template<class T> T offbit(T s, int i) {
    return s & (~(T(1) << i));
}
template<class T> int cntbit(T s) {
    return s == 0 ? 0 : cntbit(s >> 1) + (s & 1);
}

const int bfsz = 1 << 16;
char bf[bfsz + 5];
int rsz = 0;
int ptr = 0;
char gc() {
    if (rsz <= 0) {
        ptr = 0;
        rsz = (int) fread(bf, 1, bfsz, stdin);
        if (rsz <= 0)
            return EOF;
    }
    --rsz;
    return bf[ptr++];
}
void ga(char &c) {
    c = EOF;
    while (!isalpha(c))
        c = gc();
}
int gs(char s[]) {
    int l = 0;
    char c = gc();
    while (isspace(c))
        c = gc();
    while (c != EOF && !isspace(c)) {
        s[l++] = c;
        c = gc();
    }
    s[l] = '\0';
    return l;
}
template<class T> bool gi(T &v) {
    v = 0;
    char c = gc();
    while (c != EOF && c != '-' && !isdigit(c))
        c = gc();
    if (c == EOF)
        return false;
    bool neg = c == '-';
    if (neg)
        c = gc();
    while (isdigit(c)) {
        v = v * 10 + c - '0';
        c = gc();
    }
    if (neg)
        v = -v;
    return true;
}

typedef pair<int, int> II;
const ld PI = acos(-1.0);
const ld eps = 1e-9;
const int dr[] = { -1, 0, +1, 0};
const int dc[] = { 0, +1, 0, -1};
const int inf = (int) 1e9 + 5;
const ll linf = (ll) 1e16 + 5;
const int mod = (ll) (1e9 + eps);
#define ok puts("ok")
#define maxn 20005
#define maxe 200005

int n, m, k;
int adj[maxe], next[maxe], last[maxn], cost[maxe], E = 0;
ll f[maxn][22];

void add(int u, int v, int c){
	adj[E] = v; cost[E] = c; next[E] = last[u]; last[u] = E++;
	adj[E] = u; cost[E] = c; next[E] = last[v]; last[v] = E++;
}

int main(){
//	freopen("in.txt", "r", stdin);
	scanf("%d %d %d", &n, &m, &k);
	int u, v, c, num;
	ms(last, -1); E = 0;
	Rep(run, m){
		scanf("%d %d %d", &u, &v, &c);
		add(u, v, c);
	}

	ms(f, 0x3f);
	For(i, 0, k) f[1][i] = 0;
	priority_queue<pair<ll, II> > que;
	que.push(mp(0, mp(1, 0)));
	ll C, res = linf;

	while(!que.empty()){
		C = -que.top().fi; u = que.top().se.fi; num = que.top().se.se; que.pop();
		if(f[u][num] < C) continue;
		if(u == n){
			res = f[n][num];
			break;
		}
		for(int e = last[u]; e != -1; e = next[e]){
			v = adj[e];
			if(f[v][num] > C + cost[e]){
				f[v][num] = C + cost[e];
				que.push(mp(-f[v][num], mp(v, num)));
			}

			if(num < k && f[v][num + 1] > C){
				f[v][num + 1] = C;
				que.push(mp(-f[v][num + 1], mp(v, num + 1)));
			}
		}
	}

	cout << res;

	return 0;
}

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