POJ 3903 Stock Exchange 解题心得

#include<iostream>
#include<cstdio>
using namespace std;
const int N = 100000 + 10;

int a[N], dp[N];

//                                                                    while循环实现
int binsearch(int *d, int left, int right, int key)
{
    int  mid;
    while (left <= right)
    {
        mid = left + ((right - left) >>1);
        if (d[mid] < key&&d[mid + 1] >= key)
            return mid;
        if (d[mid] < key&&d[mid + 1] < key)
            left = mid + 1;
        if (d[mid] == key)
            right = mid - 1;
        if (d[mid]>key)
            right = mid - 1;
    }
    return  -1;
}
//                                                                                递归实现
//int binsearch(int *d,int left, int right, int key)
//{
//    //     搜索区间   [left ,right]
//    
//    if (left > right)
//        return -1;
//
//    int mid = left+(right-left)/2;
//    if (d[mid] < key&&d[mid + 1] >= key)
//        return mid;
//    if (d[mid] == key)
//        right = mid - 1;
//
//    else if (d[mid] < key){                    //可以优化？
//        left = mid+1;                
//    }
//    else if(d[mid]>key){
//        right = mid - 1;
//    }
//    return binsearch(d, left, right, key);
//}

int main()
{
    //int aa[N] = { 1, 1, 1, 1, 1 };
    //cout << binsearch(aa, 0, 5, 1);
    int n;
    while (cin >> n)
    {
        for (int i = 0; i < n; i++)
        {
            scanf("%d", a + i);
        }
        dp[1] = a[0];
        int len = 1, protected_len;
        for (int i = 1; i < n; i++)
        {
            if (i == 3)
                int oiu=3;
            if (a[i]>dp[len]){
                len++;
                dp[len] = a[i];
            }
            else{
                protected_len = binsearch(dp,1,len,a[i]);
                //cout << "protencetd=" << protected_len << ‘ ‘ << a[i] << endl;
                if (protected_len != -1){
                    protected_len++;
                    dp[protected_len] = a[i];
                }
                else{
                    dp[1] = a[i];
                }
            }
        }
        cout << len << endl;
    }
    return 0;
}