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QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#663811 | #7883. Takeout Delivering | 111111qqqqqq | WA | 143ms | 56744kb | C++23 | 2.2kb | 2024-10-21 17:34:56 | 2024-10-21 17:34:57 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define cmin(a,b) a=min(a,b)
#define cmax(a,b) a=max(a,b)
#define modd(a,b) a=a%b
#define pb push_back
#define db double
#define lowbit(x) x&(-x)
#define cerr(x) cout<<#x<<"="<<x<<endl
const ll mod=1e9+7;
ll ksm(ll a,ll b) {ll ans=1,bs=a;while(b) {if(b&1) ans=ans*bs%mod;bs=bs*bs%mod;b>>=1;}return ans;}
#define fi first
#define se second
#define N 300010
#define M 1000010
int n,m;
int fa[N],tot=0;
int dep[2][N];
ll dis[2][N];
vector<pair<int,ll>>to[N];
struct edge{int x,y;ll w;}e[M],g[M];
void add(int a,int b,ll c) {to[a].pb({b,c});}
int find(int x) {return x==fa[x]?x:fa[x]=find(fa[x]);}
void merge(int x,int y,ll w) {
int fx=find(x),fy=find(y);
if(fx==fy) return;
fa[fx]=fy;
g[++tot]=(edge){x,y,w};
}
void solve() {
cin>>n>>m;
for(int i=1;i<=n;i++) fa[i]=i;
for(int i=1;i<=m;i++) {
int a,b,c;cin>>a>>b>>c;
e[i]=(edge){a,b,c};
}
sort(e+1,e+m+1,[&](edge a,edge b){return a.w<b.w;});
for(int i=1;i<=m;i++) {
auto [x,y,w]=e[i];
merge(x,y,w);
if(tot==n-1) break;
}
for(int i=1;i<=tot;i++) {
auto [x,y,w]=g[i];
add(x,y,w),add(y,x,w);
}
auto dfs=[&](auto self,int u,int type,int fa)->void {
dep[type][u]=dep[type][fa]+1;
for(auto [v,w]:to[u]) {
if(v==fa) continue;
dis[type][v]=dis[type][u]+w;
self(self,v,type,u);
}
};
dfs(dfs,1,0,0);
dfs(dfs,n,1,0);
ll ans=1e18,tmp=0;
for(int i=1;i<=m;i++) {
auto [x,y,fir]=e[i];
if(x==1 && y==n) cmin(ans,fir);
if(x==n && y==1) cmin(ans,fir);
ll sec;
if(dep[0][x]>dep[0][y]) swap(x,y);
sec=min(dis[0][x]+dis[1][y],dis[1][x]+dis[0][y]);
cmin(ans,fir+sec);
}
// for(int i=1;i<=n;i++) cout<<dis[1][i]<<" ";cout<<endl;
cout<<ans<<endl;
}
int main() {
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
// int T;
// cin>>T;
// while(T--)
solve();
return 0;
}
/*
最大值可以看作是枚举当前的最大值然后2个端点分别和1,n进行取max然后加和即可
*/
详细
Test #1:
score: 100
Accepted
time: 1ms
memory: 7788kb
input:
4 6 1 2 2 1 3 4 1 4 7 2 3 1 2 4 3 3 4 9
output:
5
result:
ok 1 number(s): "5"
Test #2:
score: -100
Wrong Answer
time: 143ms
memory: 56744kb
input:
300000 299999 80516 80517 597830404 110190 110191 82173886 218008 218009 954561262 250110 250111 942489774 66540 66541 156425292 34947 34948 239499776 273789 273790 453201232 84428 84429 439418398 98599 98600 326095035 55636 55637 355015760 158611 158612 684292473 43331 43332 43265001 171621 171622 ...
output:
149949075068663
result:
wrong answer 1st numbers differ - expected: '1999991697', found: '149949075068663'