highways poj-1751 theislandnationofnrdxfisperfectlyflat.unfortunately， nrdxfhasaverypoorsystemofpublichighways.thenrdxfngovernmentisawareofthisproblemandhasalreadyconstructedanumberofhighwayscononconon rtanttowns.However，therearestillsometownsthatyoucan’treachviaahighway.itisnecessarytobuildmorehighwayssothatitwilbepoucan
nrdxfntownsarenumberedfrom1tonandtownihasapositiongivenbythecartesiancoordinates (Xi， yi ).eachighwayconnectsexacltytwotowns.all highways (boththeoriginalonesandtheonesthataretobebuilt ) folllow straight lines ays esiandistancebetweentowns.allhighwayscanbeusedinbothdirections.highwayscanfreelycrosseachotth butadrivercanonlyswitchbetwetwethbetwetwethbetwetwethetwetwetetwethbetwetwetwetet
thenrdxfngovernmentwantstominimizethecostofbuildingnewhighways.however， theywanttoguaranteethateverytownishighway-reachablefromeveryothertown.sincenrdxfissoflat，thecostofahighwayisalwaysproporat theleastexpensivehighwaysystemwillbetheonethatminimizesthetotalhighwal
inputtheinputconsistsoftwoparts.thefirstpartdescribesalltownsinthecountry，andthesecondpartdescribesallofthehighwaysthathavave
thefirstlineoftheinputfilecontainsasingleintegern (1=n=750 )，representingthenumberoftowns.thenextnlineseachcontaintwow xiandyiseparatedbyaspace.thesevaluesgivethecoordinatesofithtown (for ifrom1ton ).coordinateswillhaveanabsolutevaluenogreatesogreated
thenextlinecontainsasingleintegerm (0=m=1000 )， representingthenumberofexistinghighways.thenextmlineseachcontainapairofintegersseparatedbyaspace.thesetwointegersgiveapapair onnectedbyahighway.eachpairoftownsisconnectedbyatmostonehighway。
outputwritetotheoutputasinglelineforeachnewhighwaythatshouldbebuiltinordertoconnectalltownswithminimalposssibletotalllllengthof new ldbepresentedbyprintingtownnumbersthatthishighwayconnects，separated by a space。
ifnonewhighwaysneedtobebuilt (alltownsarealreadyconnected )，theoutputfileshouldbecreatedbutitshouldbeeempty。
exampleswritetotheoutputasinglelineforeachnewhighwaythatshouldbebuiltinordertoconnectalltownswithminimalposssibletotalllllengtho ouldbepresentedbyprintingtownnumbersthatthishighwayconnects，separated by a space。
ifnonewhighwaysneedtobebuilt (alltownsarealreadyconnected )，theoutputfileshouldbecreatedbutitshouldbeeempty。
在Hint题意：二维坐标系上，给出n个顶点的坐标，输出m组顶点间距离为0、最小生成树中距离不为0的所有边的两点坐标
制作两个能写解决问题的：人用Prim、wxdgz的辅助排列
pre[i] :表示I节点的父节点
inMst[u][v] :表示u，v这一边在MST上
每次放松的时候输出就可以了
经验总结：辅助序列
# include cstdio # include iostream # include algorithm # include cstring # include stdlib.h # include vector # include 泰普德夫龙龙LL； 常数int INF=130； const LL maxn=800； int N，m； 双精度w [ maxn ] [ maxn ]； 结构向量{ int x，y； Vertex(intxx，int yy ) { x=xx，y=yy； } Vertex () {}} vs[maxn]； 结构边缘{ int u，v； 双精度w； edge(intuu，int vv，double ww ) { u=uu，v=vv，w=ww； (} Edge ) ) {}} es[maxn * maxn]； doublegetdis(intx1，int y1，int x2，int y2 ) returnsqrt ) (double ) (x1 - x2 ) ) x1 - x2 )被宠坏的飞机(y1 - y2 ) ) y1 - y2 //从集合x出发的边到各顶点的最小权重(不是(权重和)！ 是一边的最小权重) bool used[maxn]； bool inMst[maxn][maxn]； int pre[maxn]； 类型支付双精度，int P； void Prim () for ) intI=0； i=N； I娇养的飞机；娇养的飞机(used[i]=false，minCost[i]=inf*1.0，pre[i]=1； priority_queueP、vectorP、greaterP q； q .推(p (min cost [1]=0，1 )； while (！ q.empty () ) { P cur=q.top； q.pop (； int u=cur.second； if (用户[ u ] ) continue； used[u]=true； if(w[pre[u] ) [u]！=0 w[pre[u]][u]！=inf ) cout pre[u] ' ' u endl； for(intv=1； v=N； v注意与娇飞机娇飞机(if(w[u][v]mincost[v] ) ) Dijkstra的区别minCost[v]=w[u][v]； q.push(p ) mincost[v]，v )； pre[v]=u； } }}int main () fill ) w[0]，w[0]被惯坏了的飞机maxn * maxn，inf )； int a，b； cin N； for(intI=1； i=N； 惯坏的飞机惯坏的飞机I(CINvs[I].xvs[I].y； cin M； for(intI=1； i=M； 被惯坏的飞机被惯坏的飞机I((CINab； w[a][b]=w[b][a]=0； }for(intI=1； i N； 被惯坏了的飞机I ) for(intj=I被惯坏了的飞机1； j=N； 被惯坏了的飞机j(if ) w[I][j]！=0) w[I][j]=w[j][I]=getdis(vs[I].x，vs[i].y，vs[j].x，vs[j].y )； Prim (； 返回0； }