思路:把红边设为1,蓝边设为2,求一次红色优先的最小生成树,得出最少的蓝边数,再蓝色优先求一次最小生成树,得出最多的蓝边数,最后只要K在这个范围内就可以
code:
/* ID:yueqi LANG:C++ TASK:humble */ #include <set> #include <map> #include <ctime> #include <queue> #include <cmath> #include <stack> #include <limits.h> #include <vector> #include <bitset> #include <string> #include <cstdio> #include <cstring> #include <fstream> #include <string.h> #include <iostream> #include <algorithm> #define Si set<int> #define LL long long #define pb push_back #define PS printf(" ") #define Vi vector<int> #define LN printf("\n") #define lson l,m,rt << 1 #define rson m+1,r,rt<<1|1 #define SD(a) scanf("%d",&a) #define PD(a) printf("%d",a) #define SET(a,b) memset(a,b,sizeof(a)) #define FF(i,a) for(int i(0);i<(a);i++) #define FD(i,a) for(int i(a);i>=(1);i--) #define FOR(i,a,b) for(int i(a);i<=(b);i++) #define FOD(i,a,b) for(int i(a);i>=(b);i--) #define readf freopen("humble.in","r",stdin) #define writef freopen("humble.out","w",stdout) const int maxn = 1001; const long long BigP=999983; const long long INF = 0x5fffffff; const int dx[]={-1,0,1,0}; const int dy[]={0,1,0,-1}; const double pi = acos(-1.0); const double eps= 1e-7; using namespace std; int N,M,K,father[maxn],rank[maxn]; struct edge{ int u,v; int col;//col==1 red,col==2 blue; }Edge[maxn*maxn]; bool cmp1(const edge a,const edge b){ return a.col<b.col; } bool cmp2(const edge a,const edge b){ return a.col>b.col; } void initUnion(){ FOR(i,1,N){ father[i]=i; rank[i]=0; } } int find(int k){ return k==father[k] ? k:father[k]=find(father[k]); } void Union(int x,int y){ if(rank[x]<rank[y]){ father[x]=y; }else{ father[y]=x; if(rank[x]==rank[y]) rank[x]++; } } int kruskal(){ int blue_cnt=0; int cnt=0; FOR(i,1,M){ int x=find(Edge[i].u); int y=find(Edge[i].v); if(x!=y){ Union(x,y); cnt++; if(Edge[i].col==2) blue_cnt++; if(cnt==N-1) break; } } return blue_cnt; } int main(){ while(~scanf("%d%d%d",&N,&M,&K)&&(N+M+K)){ initUnion(); char buf[2]; int u,v; FOR(i,1,M){ scanf("%s",buf); scanf("%d%d",&u,&v); Edge[i].u=u; Edge[i].v=v; if(buf[0]=='R') Edge[i].col=1; else Edge[i].col=2; } //最小蓝色生成树 sort(Edge+1,Edge+M+1,cmp1); int minn=kruskal(); initUnion(); //最小红色 sort(Edge+1,Edge+M+1,cmp2); int maxx=kruskal(); if(K>=minn&&K<=maxx) puts("1"); else puts("0"); } return 0; }