AcWing 3996. 涂色 java 区间DP （过程比结果更重要）

🤠 原题地址


⭐ 预先压缩数组
⭐ 局部的最小值 >= 全局最小值

import java.util.Scanner;

public class Main
{
	static int N = 5010;
	static int[] color = new int[N];
	static int[][] f = new int[N][N];

	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		color[1] = sc.nextInt();
		int last = color[1];

		int idx = 1;
		for (int i = 2; i <= n; i++)
		{
			int x = sc.nextInt();
			if (x != last)
				color[++idx] = x;
			last = color[idx];
		}

		n = idx;

		for (int len = 2; len <= n; len++)
		{
			for (int l = 1, r = l + len - 1; r <= n; l++, r++)
			{
				if (color[l] == color[r])
					f[l][r] = f[l + 1][r - 1] + 1;
				else
				{
					f[l][r] = Math.min(f[l + 1][r], f[l][r - 1]) + 1;
				}
			}
		}

		System.out.println(f[1][n]);
	}
}