poj 1201(查分約束之spfa)
Intervals
Time Limit: 2000MS
Memory Limit: 65536K
Total Submissions: 21758
Accepted: 8191
Description
You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn.
Write a program that:
reads the number of intervals, their end points and integers c1, ..., cn from the standard input,
computes the minimal size of a set Z of integers which has at least ci common elements with interval [ai, bi], for each i=1,2,...,n,
writes the answer to the standard output.
Input
The first line of the input contains an integer n (1 <= n <= 50000) -- the number of intervals. The following n lines describe the intervals. The (i+1)-th line of the input contains three integers ai, bi and ci separated by single spaces and such that 0 <=
ai <= bi <= 50000 and 1 <= ci <= bi - ai+1.
Output
The output contains exactly one integer equal to the minimal size of set Z sharing at least ci elements with interval [ai, bi], for each i=1,2,...,n.
Sample Input
5
3 7 3
8 10 3
6 8 1
1 3 1
10 11 1
Sample Output
6
Source
Southwestern Europe 2002
AC代碼：
#include
#include
#include
#include
using namespace std;
struct Node{
int v,w;
int next;
}Edge[150010];
int n,k;
int mx,mn;
int head[50005];
int spfa(){
stack st;
int vis[50005],dis[50005];
for(int i=mn;i<=mx;i++){
vis[i]=0;
dis[i]=-999999;
}
dis[mn]=0;
st.push(mn);
while(!st.empty()){
int u=st.top(); st.pop();
vis[u]=0;
for(int i=head[u];i;i=Edge[i].next){
int v=Edge[i].v;
if(dis[v]
