bzoj 1576（dijkstra+并查集）

传送门
题意：给定一个无向图，图中点1到任意一点的最短路唯一，问把到每个点最短路上的最后一条边去掉之后的最短路是多少。

#include<bits/stdc++.h>using namespace std;const int maxn=1e5+2,maxm=2e5+2,INF=0x3f3f3f3f;int n,m;int head[maxn],dis[maxn],fa[maxn],h[maxn],ans[maxn],edge=0;struct EDGE {    int u,v,nxt,w;}e[maxm<<1];struct A {    int x,y,z;    friend bool operator <(const A &ff,const A &hh) {        return ff.z<hh.z;    }}a[maxm<<1];int cnt=0,temp;struct NODE {    int id,dis;    friend bool operator <(const NODE &ff,const NODE &hh) {        return ff.dis>hh.dis;    }};inline int read() {    int x=0;char c=getchar();    while (c<'0'||c>'9') c=getchar();    while (c>='0'&&c<='9') x=x*10+c-'0',c=getchar();    return x;}inline void adde(int u,int v,int w) {    e[edge].u=u,e[edge].v=v,e[edge].w=w,e[edge].nxt=head[u],head[u]=edge++;    e[edge].u=v,e[edge].v=u,e[edge].w=w,e[edge].nxt=head[v],head[v]=edge++;}inline void dijkstra(int source) {    memset(dis,INF,sizeof(dis)),dis[source]=0;    priority_queue<NODE> q;    NODE a={1,0};    q.push(a);    while (!q.empty()) {        a=q.top();q.pop();        int p=a.id;        for (int i=head[p];~i;i=e[i].nxt) {            int v=e[i].v;            if (dis[v]>dis[p]+e[i].w) {                dis[v]=dis[p]+e[i].w,fa[v]=p;                NODE b={v,dis[v]};                q.push(b);            }        }    }}int num(int p) {    if (h[p]) return h[p];    return num(fa[p])+1;}int Merge(int x,int y) {    if (x==y) return x;    if (h[x]<h[y]) x^=y^=x^=y;    ans[x]=(~ans[x])?ans[x]:(temp-dis[x]);    return fa[x]=Merge(fa[x],y);}int main() {//  freopen("bzoj 1576.in","r",stdin);    memset(head,-1,sizeof(head));    memset(h,0,sizeof(h));    memset(ans,-1,sizeof(ans));    n=read(),m=read();    for (register int i=1;i<=m;++i) {        int u=read(),v=read(),w=read();        adde(u,v,w);    }    dijkstra(1);    fa[1]=h[1]=1;    for (register int i=2;i<=n;++i)        h[i]=num(i);    for (register int i=0;i<edge;i+=2) {        int u=e[i].u,v=e[i].v,w=e[i].w;        if (dis[u]>dis[v]) u^=v^=u^=v;        if (dis[u]+w==dis[v]) continue;        a[++cnt]=(A){u,v,dis[u]+dis[v]+w};    }    sort(a+1,a+cnt+1);    for (register int i=1;i<=cnt;++i) {        int x=a[i].x,y=a[i].y;        temp=a[i].z;        x=Merge(x,y);    }    for (register int i=2;i<=n;++i)        printf("%d\n",ans[i]);    return 0;}