POJ - 1733 离散化 并查集

题意:求问数列区间奇偶信息正确与否

和上一题一样(甚至弱化),加个离散就ok啦

#include<iostream>

#include<algorithm>

#include<cstdio>

#include<cstring>

#include<cstdlib>

#include<cmath>

#include<string>

#include<vector>

#include<stack>

#include<queue>

#include<set>

#include<map>

#define rep(i,j,k) for(register int i=j;i<=k;i++)

#define rrep(i,j,k) for(register int i=j;i>=k;i--)

#define erep(i,u) for(register int i=head[u];~i;i=nxt[i])

#define iin(a) scanf("%d",&a)

#define lin(a) scanf("%lld",&a)

#define din(a) scanf("%lf",&a)

#define s0(a) scanf("%s",a)

#define s1(a) scanf("%s",a+1)

#define print(a) printf("%lld",(ll)a)

#define enter putchar('\n')

#define blank putchar(' ')

#define println(a) printf("%lld\n",(ll)a)

#define IOS ios::sync_with_stdio(0)

using namespace std;

const int maxn = 2e5+11;

const int oo = 0x3f3f3f3f;

const double eps = 1e-7;

typedef long long ll;

ll read(){

    ll x=0,f=1;register char ch=getchar();

    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}

    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}

    return x*f;

}

int p[maxn],r[maxn];

void init(int n){

	memset(r,0,sizeof r);

	rep(i,0,n+2) p[i]=i;

}

int find(int x){

	if(x==p[x])return x;

	int oldp=p[x];

	int t=find(p[x]);

	r[x]=(r[x]+r[oldp])&1;

	return p[x]=t;

}

void link(int fa,int fb,int a,int b,int w){

	p[fb]=fa;

	r[fb]=(r[a]-r[b]+w+4)&1;

}

int b[maxn],n,m,tot;

struct P{

	int a,b;

	bool odd;

}a[maxn];

char s[66];

inline int pos(int i){

	return lower_bound(b+1,b+1+tot,i)-b;

}

int main(){

	while(cin>>n>>m){

		tot=0;

		rep(i,1,m){

			scanf("%d%d%s",&a[i].a,&a[i].b,s);

			if(s[0]=='e')a[i].odd=0;

			else a[i].odd=1;

			if(a[i].a>a[i].b)swap(a[i].a,a[i].b);

			a[i].a--;

			b[++tot]=a[i].a;

			b[++tot]=a[i].b;

		}

		sort(b+1,b+1+tot);

		int nn=unique(b+1,b+1+tot)-b-1;

		tot=nn;

		init(nn);

		int flag=0;

		rep(i,1,m){

			int x=pos(a[i].a),y=pos(a[i].b);

			int odd=a[i].odd;

			int fx=find(x),fy=find(y);

			if(flag)continue;

			if(fx==fy){

				if((r[y]-r[x]+4&1)!=odd){

					flag=i;

				}

			}else{

				link(fx,fy,x,y,odd);

			}

		}

		printf("%d\n",flag==0?m:flag-1);

	}

	return 0;

}