Submission #97157

#	Time	Username	Problem	Language	Result	Execution time	Memory
97157		dndhk	Pipes (CEOI15_pipes)	C++14	100 / 100	1594 ms	8332 KiB

pipes

#include <iostream>
#include <vector>
#include <stdio.h>
#include <algorithm>

#define MAX_N 100000

using namespace std;

int N, M;
struct S{
	int x, y;
	bool operator <(const S &a)const{
		if(x==a.x)return y<a.y;
		return x<a.x;
	}
};
S gp[MAX_N*4+1];
int sz = 0;
int g1[MAX_N+1], g2[MAX_N+1];
int up[MAX_N+1], lv[MAX_N+1], p[MAX_N+1];
int v[MAX_N+1];
int sz2;
int a, b, A, B;
int s, e, m;

void dfs(int x){
	bool tf = true;
	up[x] = lv[x];
	s = 0, e = sz-1;
	while(s<e){
		m = (s+e)/2;
		if(gp[m].x<x) s = m+1;
		else	e = m;
	}
	for(int i=s; i<sz; i++){
		if(gp[i].x!=x)	break;
		if(gp[i].y==p[x] && tf){
			tf = false; continue;
		}	
		if(lv[gp[i].y]!=0){
			up[x] = min(up[x], lv[gp[i].y]);
		}else{
			p[gp[i].y] = x;
			lv[gp[i].y] = lv[x]+1;
			dfs(gp[i].y);
			if(up[gp[i].y]>lv[x])	printf("%d %d\n", gp[i].y, x);
			up[x] = min(up[x], up[gp[i].y]);
		}
	}
}

int main(){
	scanf("%d %d", &N, &M);
	for(int i=1; i<=N; i++)	g1[i] = g2[i] = i;
	while(M--){
		scanf("%d%d", &a, &b);
		A = a;
		while(g1[A]!=A){
			v[sz2++] = A; A = g1[A];
		}
		while(sz2>0){
			g1[v[--sz2]] = A;
		}
		B = b;
		while(g1[B]!=B){
			v[sz2++] = B; B = g1[B];
		}
		while(sz2>0){
			g1[v[--sz2]] = B;
		}
		if(A!=B){
			gp[sz].x = a; gp[sz].y = b; sz++;
			gp[sz].x = b; gp[sz].y = a; sz++;
			g1[A] = B;
			continue;
		}
		A = a; B = b;
		while(g2[A]!=A){
			v[sz2++] = A; A = g2[A];
		}
		while(sz2>0){
			g2[v[--sz2]] = A;
		}
		while(g2[B]!=B){
			v[sz2++] = B; B = g2[B];
		}
		while(sz2>0){
			g2[v[--sz2]] = B;
		}
		if(A!=B){
			gp[sz].x = a; gp[sz].y = b; sz++;
			gp[sz].x = b; gp[sz].y = a; sz++;
			g2[A] = B;
		}
	}sort(gp, gp+sz);
	for(int i=1; i<=N; i++){
		if(lv[i]==0){
			lv[i] = 1;
			dfs(i);
		}
	}
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:54:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:57:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10