【ACM-ICPC 2018 南京赛区网络预赛 L】Magical Girl Haze

【链接】 我是链接,点我呀:)
【题意】

【题解】

【代码】

#include <bits/stdc++.h>
#define LL long long
#define ms(a,b) memset(a,b,sizeof a)
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
const LL mod=1000000007;
LL powmod(LL a,LL b) {LL res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
LL gcd(LL a,LL b) { return b?gcd(b,a%b):a;}
// head
using namespace std;

const int N = 1e5;
const int K = 10;
const int M = 2e5;

struct abc
{
    int en,w,nex;
}bian[M+10];

int n,m,k,fir[N+10],totm;

LL dis[N+10][K+5];

multiset< pair<LL,pair<int,int> > > myset;

multiset< pair<LL,pair<int,int> > >::iterator it;

int main(){
    while (n>0){
        n/=2;
        n++;
        n--;
        n/=2;
    }
	ios::sync_with_stdio(0),cin.tie(0);
	int T;
	cin >> T;
	while (T--){
        memset(fir,255,sizeof fir);
        totm = 0;
        cin >> n >> m >> k;
        rep1(i,1,m){
            int x,y,z;
            cin >> x >> y >> z;
            totm++;
            bian[totm].nex = fir[x];
            fir[x] = totm;
            bian[totm].en = y;
            bian[totm].w = z;
        }
        memset(dis,255,sizeof dis);
        dis[1][0] = 0;
        myset.insert(make_pair(0,make_pair(1,0)));
        while (!myset.empty()){
            pair<LL,pair<int,int> > temp = (*myset.begin());
            myset.erase(myset.begin());
            int x = temp.second.first,times = temp.second.second;

            for (int i = fir[x];i!=-1;i = bian[i].nex)
            {
                int y = bian[i].en;LL w = bian[i].w;
                if (dis[y][times]==-1 || dis[y][times]>dis[x][times]+w){
                    if (dis[y][times]!=-1){
                        it = myset.find(make_pair(dis[y][times],make_pair(y,times)));
                        myset.erase(it);
                    }
                    dis[y][times] = dis[x][times]+w;
                    myset.insert(make_pair(dis[y][times],make_pair(y,times)));
                }
                if (times+1<=k && ( dis[y][times+1]==-1 || dis[y][times+1]>dis[x][times]))
                {
                    if (dis[y][times+1]!=-1)
                    {
                        it = myset.find(make_pair(dis[y][times+1],make_pair(y,times+1)));
                        myset.erase(it);
                    }
                    dis[y][times+1] = dis[x][times];
                    myset.insert(make_pair(dis[y][times+1],make_pair(y,times+1)));
                }
            }
        }
        LL mi = dis[n][0];
        for (int i = 1;i <= k;i++)
            if (dis[n][i]!=-1){
                mi = min(mi,dis[n][i]);
            }
        cout<<mi<<endl;
	}
	return 0;
}