题目链接：https://vjudge.net/problem/POJ-1733
解题思路：并查集+离散化
AC代码：
1 #include <iostream> 2 #include <cstdio> 3 #include <vector> 4 #include <algorithm> 5 #include <map> 6 #include <cstring> 7 #include <cmath> 8 using namespace std; 9 const int maxn=15000; 10 struct query{ 11 int l,r; 12 int oe; 13 }q[maxn]; 14 map<int,int> lists; 15 int v[maxn],fa[maxn]; 16 int finds(int t){ 17 if(fa[t]==-1) 18 return t; 19 int tmp=finds(fa[t]); 20 v[t]^=v[fa[t]]; 21 return fa[t]=tmp; 22 } 23 int main(){ 24 // freopen("in.txt","r",stdin); 25 // freopen("out.txt","w",stdout); 26 int vals[maxn<<1]; 27 char ooe[10]; 28 int ques,len; 29 memset(fa,-1,sizeof(fa)); 30 memset(v,0,sizeof(v)); 31 scanf("%d",&len); 32 scanf("%d",&ques); 33 int j=1; 34 for(int i=1;i<=ques;i++){ 35 scanf("%d%d%s",&q[i].l,&q[i].r,ooe); 36 q[i].l-=1; 37 if(ooe[0]=='e') q[i].oe=0; 38 else q[i].oe=1; 39 vals[j]=q[i].l; j++; 40 vals[j]=q[i].r; j++; 41 } 42 sort(vals+1,vals+j); 43 int m=unique(vals+1,vals+j)-vals-1; 44 for(int i=1;i<=m;i++){ 45 lists[vals[i]]=i; 46 } 47 int ending=0; 48 for(int i=1;i<=ques;i++){ 49 int t1=finds(lists[q[i].l]),t2=finds(lists[q[i].r]); 50 int vl=v[lists[q[i].l]],vr=v[lists[q[i].r]]; 51 if(t1==t2){ 52 if(vr^vl!=q[i].oe){ 53 printf("%d ",i-1); 54 ending=1; 55 break; 56 } 57 } 58 else{ 59 fa[t2]=t1; 60 v[t2]=q[i].oe^vl^vr; 61 } 62 } 63 if(!ending) printf("%d ",ques); 64 return 0; 65 }
额，先这样吧，晚上或者明天再来详谈。