P1462 通往奥格瑞玛的道路(最短路)

一张无向图,边有边权,点有点权,每经过一条边会失去一些血量

问你在血量时刻非负的情况下,到达终点路径上经过的所有点的点权的最大值的最小值

有重边,不能抵达输出AFK

二分经过点权的最大值,每个二分都重建图跑dij,点权超限的点不能连边

一开始没判AFK以及dij写错了居然得了60

代码:

#include <bits/stdc++.h>
#define int long long
#define sc(a) scanf("%lld",&a)
#define scc(a,b) scanf("%lld %lld",&a,&b)
#define sccc(a,b,c) scanf("%lld %lld %lld",&a,&b,&c)
#define schar(a) scanf("%c",&a)
#define pr(a) printf("%lld",a)
#define fo(i,a,b) for(int i=a;i<b;++i)
#define re(i,a,b) for(int i=a;i<=b;++i)
#define rfo(i,a,b) for(int i=a;i>b;--i)
#define rre(i,a,b) for(int i=a;i>=b;--i)
#define prn() printf("\n")
#define prs() printf(" ")
#define mkp make_pair
#define pii pair<int,int>
#define pub(a) push_back(a)
#define pob() pop_back()
#define puf(a) push_front(a)
#define pof() pop_front()
#define fst first
#define snd second
#define frt front()
#define bak back()
#define mem0(a) memset(a,0,sizeof(a))
#define memmx(a) memset(a,0x3f3f,sizeof(a))
#define memmn(a) memset(a,-0x3f3f,sizeof(a))
#define debug
#define db double
#define yyes cout<<"YES"<<endl;
#define nno cout<<"NO"<<endl;
using namespace std;
typedef vector<int> vei;
typedef vector<pii> vep;
typedef map<int,int> mpii;
typedef map<char,int> mpci;
typedef map<string,int> mpsi;
typedef deque<int> deqi;
typedef deque<char> deqc;
typedef priority_queue<int> mxpq;
typedef priority_queue<int,vector<int>,greater<int> > mnpq;
typedef priority_queue<pii> mxpqii;
typedef priority_queue<pii,vector<pii>,greater<pii> > mnpqii;
const int maxn=50005;
const int inf=0x3f3f3f3f3f3f3f3f;
const int MOD=100000007;
const db eps=1e-10;
int qpow(int a,int b){int tmp=a%MOD,ans=1;while(b){if(b&1){ans*=tmp,ans%=MOD;}tmp*=tmp,tmp%=MOD,b>>=1;}return ans;}
int lowbit(int x){return x&-x;}
int max(int a,int b){return a>b?a:b;}
int min(int a,int b){return a<b?a:b;}
int mmax(int a,int b,int c){return max(a,max(b,c));}
int mmin(int a,int b,int c){return min(a,min(b,c));}
void mod(int &a){a+=MOD;a%=MOD;}
bool chk(int now);
int half(int l,int r){while(l<=r){int m=(l+r)/2;if(chk(m))r=m-1;else l=m+1;}return l;}
int ll(int p){return p<<1;}
int rr(int p){return p<<1|1;}
int mm(int l,int r){return (l+r)/2;}
int lg(int x){if(x==0) return 1;return (int)log2(x)+1;}
bool smleql(db a,db b){if(a<b||fabs(a-b)<=eps)return true;return false;}
db len(db a,db b,db c,db d){return sqrt((a-c)*(a-c)+(b-d)*(b-d));}
bool isp(int x){if(x==1)return false;if(x==2)return true;for(int i=2;i*i<=x;++i)if(x%i==0)return false;return true;}
inline int read(){
    char ch=getchar();int s=0,w=1;
    while(ch<48||ch>57){if(ch=='-')w=-1;ch=getchar();}
    while(ch>=48&&ch<=57){s=(s<<1)+(s<<3)+ch-48;ch=getchar();}
    return s*w;
}
inline void write(int x){
    if(x<0)putchar('-'),x=-x;
    if(x>9)write(x/10);
    putchar(x%10+48);
}

int n,m,b;
int f[maxn],x[maxn],y[maxn],w[maxn],dis[maxn];
vei g[maxn],v[maxn];
bool in[maxn];

int dij(int s){
    memmx(dis);
    mem0(in);
    mnpqii q;
    dis[s]=0;
    q.push(mkp(0,s));
    while(!q.empty()){
        int x=q.top().snd;
        q.pop();
        if(in[x]) continue;
        in[x]=1;
        fo(i,0,g[x].size()){
            int y=g[x][i],val=v[x][i];
            if(dis[x]+val<dis[y]){
                dis[y]=dis[x]+val;
                q.push(mkp(dis[y],y));
            }
        }
    }
    return dis[n];
}

bool chk(int now){
    re(i,1,n) g[i].clear(),v[i].clear();
    re(i,1,m){
        if(f[x[i]]<=now&&f[y[i]]<=now) 
            g[x[i]].pub(y[i]),
            g[y[i]].pub(x[i]),
            v[x[i]].pub(w[i]),
            v[y[i]].pub(w[i]);
    }
    int ans=dij(1);
    if(ans<b) return 1;
    else return 0;
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    cin>>n>>m>>b;
    int mn=inf,mx=-inf;
    re(i,1,n) cin>>f[i],mn=min(mn,f[i]),mx=max(mx,f[i]);
    re(i,1,m) cin>>x[i]>>y[i]>>w[i];
    int ans=half(mn,mx);
    if(!chk(ans)) cout<<"AFK";
    else cout<<ans;
    return 0;
}

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转载自www.cnblogs.com/oneman233/p/11514923.html
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