# （杭电1406）完数

there is a collection of n activities e={1,2,..,n}, each of which requires the same resource, such as
a lecture venue, etc., and only one activity at a time use this resource. each activity i has a start
time of si and an end time of fi and si fi. if the activity i is selected, it occupies resources within
the time interval [si,fi). if the interval [si,fi) does not intersect the interval [sj,fj), then the activity i is
said to be compatible with the activity j. that is, when fi =sj or fj =si, the activity i is compatible
with the activity j . choose the largest collection of activities that are compatible with each other.

the first line is an integer n;
the next n line, two integers per line, si and fi.

excluding mutual and compatible maximum active number.

4
1 3
4 6
2 5
1 7

2

1 =n =1000

```#include stdio.h
struct huodong
int begin;
int end;
} j[1002];
int main
int n,i,j,sum,temp;
sum = 1;
scanf
scanf;
for
for
if
temp = j[j].end;
j[j].end = j[j+1].end;
j[j+1].end = temp;
temp = j[j].begin;
j[j].begin = j[j+1].begin;
j[j+1].begin = temp;
temp = j[0].end;
for
if
sum++;
temp = j[i].end;
printf;
return 0;
}```