hdu1950 Bridging signals 最长递增子序列

　　用一个数组记下递增子序列长度为i时最小的len[i],不断更新len数组,最大的i即为最长递增子序列的长度

 #include<cstdio>
 #include<algorithm>
 #define MAX 40010
 using namespace std;
 int a, T, n, len[MAX];
 int* lower(int &val, int R) //二分找值，返回下标
 {
     int L = , mid;
     while (L < R)
     {
         mid = R - (R - L + ) / ;            //保证至少减少1
         if (len[mid] < val)    L = mid + ;//至少增加1
         else                R = mid;
     }
     return &len[R];
 }
 int main()
 {
     scanf("%d", &T);
     while (T--)
     {
         scanf("%d", &n);
         int i, l = ;
         scanf("%d", &a);
         len[] = a;
         for (i = ; i < n; i++)
         {
             scanf("%d", &a);
             if (a>=len[l]) len[++l] = a;
             else *lower(a, l) = a;
             //            else *upper_bound(len,len+l+1,a) = a;
         }
         printf("%d\n", l + );
     }
     return ;
 }