标签：des style http color os io strong for ar
Is the Information Reliable?Crawling in process... Crawling failed Time Limit:3000MS Memory Limit:131072KB 64bit IO Format:%I64d & %I64u
Description
The galaxy war between the Empire Draco and the Commonwealth of Zibu broke out 3 years ago. Draco established a line of defense called Grot. Grot is a straight line with N defense stations. Because of the cooperation of the stations, Zibu’s Marine Glory cannot march any further but stay outside the line.
A mystery Information Group X benefits form selling information to both sides of the war. Today you the administrator of Zibu’s Intelligence Department got a piece of information about Grot’s defense stations’ arrangement from Information Group X. Your task is to determine whether the information is reliable.
The information consists of M tips. Each tip is either precise or vague.
Precise tip is in the form of P A B X, means defense station
A is X light-years north of defense station B.
Vague tip is in the form of V A B, means defense station A is in the north of defense station
B, at least 1 light-year, but the precise distance is unknown.
Input
There are several test cases in the input. Each test case starts with two integers N (0 < N ≤ 1000) and M (1 ≤ M ≤ 100000).The next M line each describe a tip, either in precise form or vague form.
Output
Output one line for each test case in the input. Output “Reliable” if It is possible to arrange N defense stations satisfying all the M tips, otherwise output “Unreliable”.
Sample Input
3 4 P 1 2 1 P 2 3 1 V 1 3 P 1 3 1 5 5 V 1 2 V 2 3 V 3 4 V 4 5 V 3 5
Sample Output
Unreliable Reliable
题意：有N个车站，给出一些点的精确信息和模糊信息，精确信息给出两点的位置和距离，模糊信息给出两点的位置，但距离大于等于一。试确定是否所有的信息满足条件
思路：对于精确信息，可以得出两个差分条件，b-a = c;可以化为b-a >= c && a - b <= -c;(因为是精确信息，故要建立双向边)
对于模糊信息，只能得出一个差分条件，可以化为 b - a <= 1;所以a <= b-1;说明b到a有一条长度为-1的边；（模糊信息，建立单向边）
#include <stdio.h> #include <string.h> #include <stdlib.h> #include <algorithm> using namespace std; #define inf 9999999999; struct node { int u,v,w; } edge[200000]; int dis[200000]; int n,m,cnt; int Bellman_ford() { int i,j; int flag; memset(dis,0,sizeof(dis)); for(i=0;i<n;i++) { flag = 0; for(j=0;j<cnt;j++) { if(dis[edge[j].v]>dis[edge[j].u]+edge[j].w) { dis[edge[j].v]=dis[edge[j].u]+edge[j].w; flag=1; } } if(!flag) break; } for(j=0;j<cnt;j++) { if(dis[edge[j].v]>dis[edge[j].u]+edge[j].w) return 1; } return 0; } int main() { int i,j; int u,v,w; char str; while(~scanf("%d %d",&n,&m)) { cnt=0; for(i=0; i<m; i++) { getchar(); scanf("%c",&str); if(str=='P') { scanf("%d %d %d",&u,&v,&w); edge[cnt].u=u; edge[cnt].v=v; edge[cnt].w=w; cnt++; edge[cnt].u=v; edge[cnt].v=u; edge[cnt].w=-w; cnt++; } else { scanf("%d %d",&u,&v); edge[cnt].u=v; edge[cnt].v=u; edge[cnt].w=-1; cnt++; } } if(Bellman_ford()) puts("Unreliable"); else puts("Reliable"); } return 0; }
Is the Information Reliable?（差分约束）
标签：des style http color os io strong for ar
原文地址：http://blog.csdn.net/u013486414/article/details/38758195
