hdu 5253 连接的管道 简单MST

题目链接

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解法：kruskal+并查集
根据数据规模不能用搜索

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#include<cstdio>#include<string>#include<cstring>#include<iostream>#include<cmath>#include<algorithm>#include<vector>using namespace std;#define all(x) (x).begin(), (x).end()#define for0(a, n) for (int (a) = 0; (a) < (n); (a)++)#define for1(a, n) for (int (a) = 1; (a) <= (n); (a)++)#define mes(a,x,s)  memset(a,x,(s)*sizeof a[0])#define mem(a,x)  memset(a,x,sizeof a)#define ysk(x)  (1<<(x))typedef long long ll;//const int INF = 0x3f3f3f3f ;const int maxn= 1000 ;int kase,T,n,m,nedge,N;int h[maxn+3][maxn+3];int dir[2][2]= { {+1,0},{0,+1} }; int par[(maxn+3)*(maxn+3)];bool in(int x,int y)  { return 1<=x&&x<=n&&1<=y&&y<=m;}int get_id(int x,int y)   {  return (x-1)*m+y; }struct Edge{    int x,y,w;    Edge(){}    Edge(int x,int y,int w):x(x),y(y),w(w){}    bool operator<(const Edge e)const    {        return w<e.w;    }}e[ 2*(maxn+3)*(maxn+3) ];void init(){    nedge=0;    for1(i,N)  par[i]=i;}int find(int x) { return x==par[x]?x:par[x]=find(par[x]); }void MST(){    sort(e,e+nedge);    // printf("nedge=%d\n",nedge);    int ans=0,cnt=0;    for(int i=0;i<nedge&&cnt<N-1;i++)    {        int x=e[i].x,y=e[i].y,w=e[i].w;        int tx=find(x),ty=find(y);        if(tx==ty)  continue;        par[tx]=ty;        ans+=w;        cnt++;        // printf("connect -----%d -------%d\n",x,y);    }    printf("Case #%d:\n%d\n",++kase,ans);}int main(){    scanf("%d",&T);    while(T--)    {        scanf("%d%d",&n,&m);N=n*m;    init();        for1(i,n) for1(j,m) scanf("%d",&h[i][j]);        for1(i,n) for1(j,m)        {            int id=get_id(i,j);            for0(k,2)            {                int ti=i+dir[k][0],tj=j+dir[k][1];                    if(!in(ti,tj))  continue;                int id2=get_id(ti,tj);                e[nedge++]=Edge(id,id2,abs(h[i][j]-h[ti][tj]) );            }        }        MST();    }    return 0;}

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长期没写代码，find函数还写错了,结果超时，return x==par[x]？x:par[x]=find(par[x])

写成了return x==par[x]?x:find(par[x])