1706: [usaco2007 Nov]relays 奶牛接力跑 倍增floyd

裸倍增floyd。。
开始sb数组开的[205]清数组清到205果断RE。
我真是弱QAQ

#include<bits/stdc++.h>#define inf 1000000007#define N 210using namespace std;int n,m,S,E,cnt;int id[1005],ans[N][N],f[N][N],t[N][N];inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline void floyd(int a[N][N],int b[N][N],int c[N][N]){    for (int k=1;k<=cnt;k++)        for (int i=1;i<=cnt;i++)            for (int j=1;j<=cnt;j++)                c[i][j]=min(c[i][j],a[i][k]+b[k][j]);}inline void save(int a[N][N],int b[N][N]){    for (int i=1;i<=cnt;i++)        for (int j=1;j<=cnt;j++)            a[i][j]=b[i][j],b[i][j]=inf;}int main(){    n=read(); m=read(); S=read(); E=read();    for (int i=1;i<=205;i++)        for (int j=1;j<=205;j++)            f[i][j]=ans[i][j]=t[i][j]=inf,ans[i][i]=0;    for (int i=1;i<=m;i++)      {        int w=read(),u=read(),v=read();        if (!id[u]) id[u]=++cnt;        if (!id[v]) id[v]=++cnt;        f[id[u]][id[v]]=f[id[v]][id[u]]=w;    }    while (n)    {        if (n&1) floyd(ans,f,t),save(ans,t);        floyd(f,f,t);        save(f,t);        n>>=1;    }    cout << ans[id[S]][id[E]];    return 0;}