最优二叉搜索树 java实现 学习 备忘

import java.util.Arrays;

public class Test {
	
	public static void main(String args[]){
		optimalBST(p, q, n);
	}
	
	
	// 5个互异关键字组成的序列，且关键字有序。
	public static int n = 5;

	// 每个关键字对应的被搜索到的概率
	public static float[] p = {0f, 0f, 0.15f, 0.10f, 0.05f, 0.10f, 0.20f};

	
	// 搜索不到的概率
	public static float[] q = {0f, 0.05f, 0.10f, 0.05f, 0.05f, 0.05f, 0.10f};

	// 由底向上处理
	public static void optimalBST(float[] p, float[] q, int n){
		float t = Float.MAX_VALUE;
		float[][] root = new float[n + 1][n + 1];
		
		float[][] e = new float[n + 2][n + 1];
		float[][] w = new float[n + 2][n + 1];
		
		for (int i = 1; i < n + 2; i++) {
			e[i][i - 1] = q[i];
			w[i][i - 1] = q[i];
		}
		
		for (int l = 1; l <= n; l++) {
			for (int i = 1; i <= n - l + 1; i++) {
				int j = i + l - 1;
				e[i][j] = Float.MAX_VALUE;
				w[i][j] = w[i][j - 1] + p[j + 1] + q[j + 1]; 
				for (int k = i; k <= j; k++) {
					t = e[i][k - 1] + e[k + 1][j] + w[i][j];
					if(t < e[i][j]){
						e[i][j] = t;
						root[i][j] = k;
					}
				}
			}
		}
		
		
		for (int i = 0; i < e.length; i++) {
			System.out.println(Arrays.toString(e[i]));
		}
		
		System.out.println("####################");
		
		for (int i = 0; i < w.length; i++) {
			System.out.println(Arrays.toString(w[i]));
		}


		System.out.println("####################");
		
		for (int i = 0; i < root.length; i++) {
			System.out.println(Arrays.toString(root[i]));
		}
	}
}