2017.11.1 模拟 communicate

​​http://www.elijahqi.win/archives/1466​​​
这题要求我们求最短路 前10分送分题 稀疏图直接spfa预处理 然后o1查询即可

然后接下来的30分时树上最短路 只要倍增求lca即可

再接下来是环套树 只要还是同时倍增到环上 然后顺着一个方向遍历一边整个环 然后o1验证两个环的大小即可 我写崩了..

好不容易改对了 忘了从机房带回家了 被还原卡还原了 导致 又写了好久

#include<cstdio>
#include<queue>
#include<cstring>
#include<algorithm>
#define N 11000
using namespace std;
inline char gc(){
    static char now[1<<16],*S,*T;
    if (T==S){T=(S=now)+fread(now,1,1<<16,stdin);if (T==S) return EOF;}
    return *S++;
}
inline int read(){
    int x=0,f=1;char ch=gc();
    while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=gc();}
    while (ch<='9'&&ch>='0'){x=x*10+ch-'0';ch=gc();}
    return x*f;
}
int f[N],flag[N],fa1[N],fa[N][20],sum[N][20],bin[20],Log[N],n,m,k,sum1[N],id[N],h[N],dep[N],circle[N],num,map[1100][1100];
struct node{
    int y,next,z;
}data[(N+1200)<<1];
inline void spfa(int u){
    queue<int> q;memset(flag,0,sizeof(flag));memset(f,0x3f,sizeof(f));f[u]=0;flag[u]=1;q.push(u);
    while (!q.empty()){
        int x=q.front();q.pop();flag[x]=0;
        for (int i=h[x];i;i=data[i].next){
            int y=data[i].y,z=data[i].z;
            if (f[x]+z<f[y]){
                f[y]=f[x]+z;
                if (!flag[y]){
                    q.push(y);flag[y]=1;
                }
            }
        }
    }
}
void dfs(int x){
    for (int i=h[x];i;i=data[i].next){
        int y=data[i].y,z=data[i].z;if (fa[x][0]==y) continue;
        dep[y]=dep[x]+1;fa[y][0]=x;sum[y][0]=z;
        for (int j=1;j<=Log[dep[y]];++j){
            fa[y][j]=fa[fa[y][j-1]][j-1];sum[y][j]=sum[y][j-1]+sum[fa[y][j-1]][j-1];
        }dfs(y);
    }
}
inline int lca(int &x,int &y){
    if (dep[x]<dep[y]) swap(x,y);int tmp=0;
    int dis=dep[x]-dep[y];
    for (int i=0;i<=Log[dis];++i) if (bin[i]&dis){tmp+=sum[x][i];x=fa[x][i];}
    if (x==y) return tmp;
    for (int i=Log[dep[y]];i>=0;--i)
        if (fa[x][i]!=fa[y][i]){tmp+=sum[x][i]+sum[y][i];x=fa[x][i];y=fa[y][i];}
    tmp+=sum[x][0]+sum[y][0];
    x=fa[x][0];y=fa[y][0];
    return tmp;
}int note,st;
void dfs1(int x){
    flag[x]=1;
    for (int i=h[x];i;i=data[i].next){
        int y=data[i].y;if (fa1[x]==y) continue;fa1[y]=x;
        if (flag[y]){circle[x]=1;st=y;note=y;break;}dfs1(y);if (note) break;
    }
    if (note==x) circle[x]=1,note=0;else if (note) circle[x]=1;
}
void dfs2(int x){
    flag[x]=1;
    for (int i=h[x];i;i=data[i].next){
        int y=data[i].y,z=data[i].z;if (fa[x][0]==y) continue;
        if (flag[y]) continue;
        if (circle[y]) dfs2(y);else{
            dep[y]=dep[x]+1;fa[y][0]=x;sum[y][0]=z;
            for (int j=1;j<=Log[dep[y]];++j){
                fa[y][j]=fa[fa[y][j-1]][j-1];sum[y][j]=sum[y][j-1]+sum[fa[y][j-1]][j-1];
            }dfs2(y);
        }
    }
}
int len;
void dfs3(int x){
    for (int i=h[x];i;i=data[i].next){
        int y=data[i].y,z=data[i].z;if (fa1[x]==y) continue;fa1[y]=x;
        if (circle[y]) {
            sum1[id[x]]=sum1[id[x]-1]+z;len+=z;if (!id[y]) {id[y]=id[x]+1;dfs3(y);}
        }
    }
}
inline int lca1(int &x,int &y){
    if (dep[x]<dep[y]) swap(x,y);int tmp=0;
    int dis=dep[x]-dep[y];
    for (int i=0;i<=Log[dis];++i) if (bin[i]&dis){tmp+=sum[x][i],x=fa[x][i];}
    if (x==y) return tmp;
    for (int i=Log[dep[y]];i>=0;--i)
        if (fa[x][i]!=fa[y][i]){
        tmp+=sum[x][i]+sum[y][i],x=fa[x][i],y=fa[y][i];
    }
    tmp+=sum[x][0]+sum[y][0];
    if (!circle[x]) x=fa[x][0];if (!circle[y]) y=fa[y][0];
    return tmp;
}
int main(){
    freopen("communicate.in","r",stdin);
    n=read();m=read();k=read();Log[0]=-1;
    for (int i=1;i<=n;++i) Log[i]=Log[i>>1]+1;
    for (int i=0;i<=Log[n]+1;++i) bin[i]=1<<i;
    for (int i=1;i<=m;++i){
        int x=read(),y=read(),z=read();
        data[++num].y=y;data[num].next=h[x];data[num].z=z;h[x]=num;
        data[++num].y=x;data[num].next=h[y];data[num].z=z;h[y]=num;
    }
    if (n<=1000){
        for (int i=1;i<=n;++i){
            spfa(i);
            for (int j=1;j<=n;++j) map[i][j]=f[j];
        }
        while (k--){
            int x=read(),y=read();
            printf("%d\n",map[x][y]);
        }return 0;
    }
    if (m==n-1){
        dfs(1);
        while(k--){
            int x=read(),y=read();
            printf("%d\n",lca(x,y));
        }return 0;
    }
    if (m==n){
        dfs1(1);memset(fa1,0,sizeof(fa1));num=0;memset(flag,0,sizeof(flag));
        dfs2(st);//for (int i=1;i<=n;++i) if(circle[i]) {dfs2(i);break;}
        memset(fa1,0,sizeof(fa1));id[st]=1;dfs3(st);
        while(k--){
            int x=read(),y=read();
            int ans=lca1(x,y);
            if (x==y) printf("%d\n",ans);else{
                x=id[x];y=id[y];
                if (x<y) swap(x,y);
                ans+=min(sum1[x-1]-sum1[y-1],len-sum1[x-1]+sum1[y-1]);
                printf("%d\n",ans);
            }
        }
    }
    return 0;
}