Uarl 1303

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PRO IS HERE

其实只是简单的贪心即可，按(x,y) 排序，然后尽量取y大的。。。

#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>#include<vector>#include<set>#include<queue>#include<map>using namespace std;#define PB push_back#define INS insert#define FOR(i,a,b) for(int (i)=(a);(i)<=(b);(i)++)#define nMax 101000#define bug puts("Fuck");int m,n;vector<int> ans;struct BB{int x,y,xx,yy;bool read(int &n){scanf("%d%d",&xx,&yy);if(xx == 0 && yy == 0) return false;if(yy<0 || xx>m) ;else n++;x = xx,y=yy;if(x<0) x = 0;if(y>m) y = m;return true;}bool operator < (const BB & b) const {if(x == b.x) return y < b.y;return x < b.x;}};BB a[nMax];int main(){//freopen("input.txt","r",stdin);//freopen("output.txt","w",stdout);while(~scanf("%d",&m)){n = 0;while(a[n].read(n));sort(a,a+n);//printf("n=%d\n",n);int l=0;ans.clear();for(int i=0;i<n;){if(l < a[i].x) break;int cp=-1,np;while(l >= a[i].x && i < n){    if(a[i].y > cp) cp=a[i].y,np=i;                i++;}if(cp <= l) continue;ans.PB(np);l = cp;}if(l < m) printf("No solution\n");else {printf("%d\n",(int)ans.size());for(int i=0;i<ans.size();i++) {printf("%d %d\n",a[ans[i]].xx,a[ans[i]].yy);}}}return 0;}