50 lines
1.4 KiB
C++
50 lines
1.4 KiB
C++
#include<iostream>
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#include<algorithm>
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using namespace std;
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#define N 200020
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struct Node {
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int x,y,lt,id ;
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}point[N];
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int n,len,maxlp[N],by[N];
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int cmp(Node a,Node b) {
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if(a.x != b.x)
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return a.x < b.x ;
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if(a.y == b.y)
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return a.lt > b.lt ;
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return a.y < b.y ;
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}
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int find(int len,int _y) {
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int mid, left = 1, right = len ;
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while(left <= right) {
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mid = (left+right) >> 1 ;
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if(by[mid] >= _y)
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right = mid-1 ;
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else left = mid+1 ;
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}
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return left ;
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}
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int main() {
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while(scanf("%d",&n) && n) {
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for(int i=0;i<n;i++) {
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scanf("%d%d",&point[2*i].x,&point[2*i].y);
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point[2*i].lt = 1 ;
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scanf("%d%d",&point[2*i+1].x,&point[2*i+1].y);
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point[2*i+1].lt = 0 ;
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point[2*i].id = point[2*i+1].id = i ;
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}
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n *= 2 ;
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sort(point,point+n,cmp) ;
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len = 0 ;
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for(int i=0;i<n;i++) {
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if(point[i].lt == 1) maxlp[point[i].id] = find(len,point[i].y) ;
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else {
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int tmp = maxlp[point[i].id] ;
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if(tmp > len) by[++len] = point[i].y ;
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else by[tmp] = min(by[tmp],point[i].y) ;
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}
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}
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printf("%d\n",len);
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}
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return 0;
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}
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