POJ 1887 Testing the CATCHER(最长非升子序列)

最新推荐文章于 2018-08-31 10:35:00 发布

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本文介绍了一种求解最长非升子序列问题的有效算法，并提供了详细的C++实现代码。该算法采用动态规划思想，通过维护一个dp数组来记录当前找到的最长非升子序列的最小结尾元素。

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题目比较长但是方法非常简单，就是求最长非升子序列。直接上代码。。。。

代码：

#include<iostream>
#include<algorithm>

using namespace std;

int dp[5000];
int num[5000];
const int inf = 0x3f3f3f3f;

int main() {
    int temp, Case = 0;
    int index = 0;
    while (cin >> temp, temp != -1) {
        num[index++] = temp;
        while (cin >> temp, temp != -1) {
            num[index++] = temp;
        }

        memset(dp, 0, sizeof(dp));

        int top = 0;
        dp[top] = inf;

        for (int i = 0; i < index; ++i) {
            if (dp[top] >= num[i]) {
                dp[++top] = num[i];
            }
            else {
                int low = 1, high = top;
                while (low <= high) {
                    int mid = (low + high) >> 1;
                    if (dp[mid] > num[i]) {
                        low = mid + 1;
                    }
                    else {
                        high = mid - 1;
                    }
                }
                dp[low] = num[i];
            }

        }
        cout << "Test #" << ++Case << ":" << endl;
        cout << "  maximum possible interceptions: " << top << endl;
        cout << endl;
        index = 0;
    }
}

这里写图片描述

#include<iostream>
#include<algorithm>

using namespace std;

int dp[5000];
int num[5000];
const int inf = 0x3f3f3f3f;

int main() {
    int temp, Case = 0;
    int index = 0;
    while (cin >> temp, temp != -1) {
        num[index++] = temp;
        while (cin >> temp, temp != -1) {
            num[index++] = temp;
        }

        for (int i = 0; i<index; i++)
        {
            dp[i] = 1;
            for (int j = 0; j<i; j++)
            {
                if (num[j] >= num[i])
                    dp[i] = max(dp[i], dp[j] + 1);
            }
        }

        int maxv = 0;
        for (int i = 0; i<index; i++)
        {
            if (dp[i]>maxv)
                maxv = dp[i];
        }

        cout << "Test #" << ++Case <<":"<< endl;
        cout << "  maximum possible interceptions: " << maxv << endl;
        cout << endl;
        index = 0;
    }
}

这里写图片描述