hdu 5141 二分法求最长上升子序列，扫描法求解

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#define MAX 100100

using namespace std;

long long a[MAX];// 存的是读取的数
long long c[MAX];//记录序列长度为下标时的结束的最靠右的元素的下标
long long dp[MAX];//记录以当前元素结尾的序列的最大长度
long long first[MAX];//记录以当前元素结尾的序列的最大长度的序列最靠右的起点
int n;
//寻找到当前节点作为末尾元素的序列最长时的长度
int bsearch ( long long num )
{
    int left = 0 , right = n , mid;
    while ( left != right )
    {
        mid = left + right >> 1;
        if ( num > a[c[mid]] && num <= a[c[mid+1]] )
            return mid;
        if ( num > a[c[mid]] ) left = mid+1;
        else right = mid;
    }
    return left;   
}

int main ( )
{
     while ( ~scanf ( "%d" , &n ) )
     {
         for ( int i = 1 ; i <= n ; i++ )
             scanf ( "%lld" , &a[i]) ;
         int ans = 0;
         memset ( c , 0 , sizeof ( c ) );
         c[0] = 100007;
         a[100007] = 0;
         a[0] = 0xffffffff;
         long long temp;
         for ( int i = 1; i <= n ; i++ )
         {
             temp  = bsearch ( a[i] );
             if ( temp == 0 ) first[i] = i;
             else first[i] = first[c[temp]];
            ( a[i] <= a[c[temp+1]] ) && (c[temp+1] = i );
            ans = max ( temp + 1, ans*1LL );
            dp[i] = temp + 1;
         }
         long long res = 0;
         for ( int i = 1 ; i <= n ; i++ )
         {
             if ( dp[i-1] == ans )
                if ( dp[i] < dp[i-1] )
                   dp[i] = dp[i-1] , first[i] = first[i-1];
             if ( dp[i] == ans ) res += first[i];
         }
         printf ( "%lld\n" , res );
     }
}