BZOJ1113: [Poi2008]海报PLA

1113: [Poi2008]海报PLA

Time Limit: 10 Sec Memory Limit: 162 MB
Submit: 691 Solved: 412
[Submit][Status]

Description

N个矩形,排成一排. 现在希望用尽量少的矩形海报Cover住它们.

Input

第一行给出数字N,代表有N个矩形.N在[1,250000] 下面N行,每行给出矩形的长与宽.其值在[1,1000000000]2 1/2 Postering

Output

最少数量的海报数.

Sample Input

5

1 2

1 3

2 2

2 5

1 4

var top,ans,i,n:longint;
a,sta:array[0..260000] of longint;
procedure init;
begin
readln(n);
for i:=1 to n do readln(a[i],a[i]);
end;
procedure main;
begin
top:=0;ans:=n;
a[n+1]:=-1;
for i:=1 to n+1 do
begin
while (top>0) and (a[i]<=a[sta[top]]) do
begin
if a[i]=a[sta[top]] then dec(ans);dec(top);
end;
inc(top);sta[top]:=i;
end;
writeln(ans);
end;
begin
assign(input,'input.txt');assign(output,'output.txt');
reset(input);rewrite(output);
init;
main;
close(input);close(output);
end.

View Code