[POJ 1609] Tiling Up Blocks

[题目链接]

            http://poj.org/problem?id=1609

[算法]

          将坐标按x为第一关键字，y为第二关键字排序 

          求最长上升子序列即可

[代码]

         

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cerrno>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <vector>
#include <cwchar>
#include <cwctype>
#include <stack>
#include <limits.h>
using namespace std;
#define MAXN 100010

struct info
{
        int x,y;
} a[MAXN];

int i,l,r,mid,n,cnt;
int q[MAXN];

inline bool cmp(info a,info b)
{
        return a.x == b.x ? a.y < b.y : a.x < b.x;
}

int main() 
{
        
        while (scanf("%d",&n) != EOF && n)
        {
                for (i = 1; i <= n; i++) scanf("%d%d",&a[i].x,&a[i].y);
                sort(a + 1,a + n + 1,cmp);
                cnt = 0;
                for (i = 1; i <= n; i++)
                {
                        if (i == 1 || a[i].y >= q[cnt]) 
                        {
                                q[++cnt] = a[i].y;
                                continue;
                        }
                        l = 1; r = cnt - 1;
                        while (l <= r)
                        {
                                mid = (l + r) >> 1;
                                if (q[mid] <= a[i].y) l = mid + 1;
                                else r = mid - 1;
                        } 
                        q[l] = a[i].y;
                }
                printf("%d\n",cnt);
        }
        printf("*\n");
        
        return 0; 
    
}