http://acm.pku.edu.cn/JudgeOnline/problem?id=1065
剛開始錯了，下面是出錯的代碼，弄清楚原因下次小心點；
#include?<iostream>
#include?<algorithm>
using?namespace?std;
struct?TanXin
{
???????int?width,?length;
}wood[5001],?record[5001];
bool?order(TanXin?a,?TanXin?b)
{
?????return??(b.width?+?b.length?>?a.width?+?a.length);
}
int?main()
{
????int?i,?j;
????int?n;
????int?t;
????int?test;
????int?l;
????int?k;
????cin?>>?test;
????while(test--)
????{?????
??????????cin?>>?n;
??????????for(i?=?0;?i?<?n;?i++)
??????????????cin?>>?wood[i].length?>>?wood[i].width;
??????????sort(wood,?wood?+?n,?order);
?????????for(i?=?0;?i?<?n;?i++)
????//??????cout?<<?wood[i].length?<<?"?"?<<?wood[i].width?<<?"?"?<<?wood[i].length?+?wood[i].width?<<?endl;
??????????record[0]?=?wood[0];
??????????l?=?1;
??????????for(i?=?1;?i?<?n;?i++)
??????????{???t?=?1;
??????????????for(j?=?0;?j?<?l;?j++)
??????????????{???
??????????????????//以下的算法錯誤，因為每次都從較小的record[0]開始覆蓋，會產生錯誤的
??????????????????//例如：?4?,3?5,?8?4,?8?5,?3?100;8，5先覆蓋3，5，所以3，?100?覆蓋不了3，?5正確答案為2，而此時為3；?
??????????????????if(wood[i].width?>=?record[j].width?&&?wood[i].length?>=?record[j].length)
??????????????????{??
?????????????????????if(wood[i].width?>?record[j].width)
???????????????????????record[j].width?=?wood[i].width;
?????????????????????if(wood[i].length?>?record[j].length)
????????????????????????record[j].length?=?wood[i].length;
?????????????????????t?=?0;
????????????????????????break;
??????????????????}
??????????????}
??????????????if(t?==?1)
??????????????{
?????????????????record[l]?=?wood[i];??
?????????????????l++;??
??????????????}
????//??????cout?<<?"record:?"?<<?l?<<?endl;
??????//??????for(k?=?0;?k?<?l;?k++)
????//?????????cout?<<?record[k].width?<<?"?"?<<?record[k].length?<<?endl;
??????????}
??????????cout?<<?l?<<?endl;
????}
????
????return?0;
}