Codeforces Round #369 (Div. 2) C. Coloring Trees

本文介绍了一个有趣的编程问题:如何以最少的涂料将未上色的树木涂成特定数量的连续同色组。需要通过动态规划算法来解决此问题。

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ZS the Coder and Chris the Baboon has arrived at Udayland! They walked in the park where n trees grow. They decided to be naughty and color the trees in the park. The trees are numbered with integers from 1 to n from left to right.

Initially, tree i has color ci. ZS the Coder and Chris the Baboon recognizes only m different colors, so 0 ≤ ci ≤ m, where ci = 0 means that tree i is uncolored.

ZS the Coder and Chris the Baboon decides to color only the uncolored trees, i.e. the trees with ci = 0. They can color each of them them in any of the m colors from 1 to m. Coloring the i-th tree with color j requires exactly pi, j litres of paint.

The two friends define the beauty of a coloring of the trees as the minimum number of contiguous groups (each group contains some subsegment of trees) you can split all the n trees into so that each group contains trees of the same color. For example, if the colors of the trees from left to right are 2, 1, 1, 1, 3, 2, 2, 3, 1, 3, the beauty of the coloring is 7, since we can partition the trees into 7 contiguous groups of the same color : {2}, {1, 1, 1}, {3}, {2, 2}, {3}, {1}, {3}.

ZS the Coder and Chris the Baboon wants to color all uncolored trees so that the beauty of the coloring is exactly k. They need your help to determine the minimum amount of paint (in litres) needed to finish the job.

Please note that the friends can't color the trees that are already colored.

Input

The first line contains three integers, n, m and k (1 ≤ k ≤ n ≤ 100, 1 ≤ m ≤ 100) — the number of trees, number of colors and beauty of the resulting coloring respectively.

The second line contains n integers c1, c2, ..., cn (0 ≤ ci ≤ m), the initial colors of the trees. ci equals to 0 if the tree number i is uncolored, otherwise the i-th tree has color ci.

Then n lines follow. Each of them contains m integers. The j-th number on the i-th of them line denotes pi, j (1 ≤ pi, j ≤ 109) — the amount of litres the friends need to color i-th tree with color j. pi, j's are specified even for the initially colored trees, but such trees still can't be colored.

Output

Print a single integer, the minimum amount of paint needed to color the trees. If there are no valid tree colorings of beauty k, print  - 1.

Examples
Input
3 2 2
0 0 0
1 2
3 4
5 6
Output
10
Input
3 2 2
2 1 2
1 3
2 4
3 5
Output
-1
Input
3 2 2
2 0 0
1 3
2 4
3 5
Output
5
Input
3 2 3
2 1 2
1 3
2 4
3 5
Output
0

代码:

#include <bits/stdc++.h>

using namespace std;
const int N=100005;
typedef long long ll;
int num[105],cost[105][105];
ll dp[105][105][105];
int main()
{
    int n,m,K;
    scanf("%d %d %d",&n,&m,&K);
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&num[i]);
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            scanf("%d",&cost[i][j]);
        }
    }
    for(int i=1;i<=n;i++)
    for(int k=0;k<=K;k++)
    {
        for(int j=0;j<=m;j++)
        {
            dp[i][k][j]=1e15;
        }
    }
    for(int k=1;k<=K;k++)
    {
        for(int j=1;j<=m;j++)
        {
            dp[0][k][j]=1e15;
        }
    }
    for(int i=1;i<=n;i++)
    {
        if(num[i]==0)
        for(int k=1;k<=K;k++)
        {
            for(int j=1;j<=m;j++)
            {
                dp[i][k][j]=min(dp[i][k][j],dp[i-1][k][j]+cost[i][j]);
                for(int q=1;q<=m;q++)
                {
                    if(q==j&&i!=1) continue;
                    dp[i][k][j]=min(dp[i][k][j],dp[i-1][k-1][q]+cost[i][j]);
                }
             //   cout<<dp[i][k][j]<<endl;
            }
        }
        else
        {
            for(int k=1;k<=K;k++)
            {
               for(int j=1;j<=m;j++)
               {
                   if(j==num[i]&&i!=1)
                   {
                       dp[i][k][num[i]]=min(dp[i][k][num[i]],dp[i-1][k][j]);
                   }
                   else
                   {
                       dp[i][k][num[i]]=min(dp[i][k][num[i]],dp[i-1][k-1][j]);

                   }//cout<<dp[i][k][j]<<endl;
               }
            }
        }
    }
    long long ans=1e15;
    for(int i=1;i<=m;i++) {ans=min(ans,dp[n][K][i]);}
    if(ans==1e15) {puts("-1");}
    else {cout<<ans<<endl;}
    return 0;
}





基于python实现的粒子群的VRP(车辆配送路径规划)问题建模求解+源码+项目文档+算法解析,适合毕业设计、课程设计、项目开发。项目源码已经过严格测试,可以放心参考并在此基础上延申使用,详情见md文档 算法设计的关键在于如何向表现较好的个体学习,标准粒子群算法引入惯性因子w、自我认知因子c1、社会认知因子c2分别作为自身、当代最优解和历史最优解的权重,指导粒子速度和位置的更新,这在求解函数极值问题时比较容易实现,而在VRP问题上,速度位置的更新则难以直接采用加权的方式进行,一个常见的方法是采用基于遗传算法交叉算子的混合型粒子群算法进行求解,这里采用顺序交叉算子,对惯性因子w、自我认知因子c1、社会认知因子c2则以w/(w+c1+c2),c1/(w+c1+c2),c2/(w+c1+c2)的概率接受粒子本身、当前最优解、全局最优解交叉的父代之一(即按概率选择其中一个作为父代,不加权)。 算法设计的关键在于如何向表现较好的个体学习,标准粒子群算法引入惯性因子w、自我认知因子c1、社会认知因子c2分别作为自身、当代最优解和历史最优解的权重,指导粒子速度和位置的更新,这在求解函数极值问题时比较容易实现,而在VRP问题上,速度位置的更新则难以直接采用加权的方式进行,一个常见的方法是采用基于遗传算法交叉算子的混合型粒子群算法进行求解,这里采用顺序交叉算子,对惯性因子w、自我认知因子c1、社会认知因子c2则以w/(w+c1+c2),c1/(w+c1+c2),c2/(w+c1+c2)的概率接受粒子本身、当前最优解、全局最优解交叉的父代之一(即按概率选择其中一个作为父代,不加权)。
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