230712 숫자 타자 대회 (refactor)

private int[][] cost;
private int[][][] dp;
private int len;
private String nums;

public int solution(String numbers) {
	initializeCost();
	len = numbers.length();
	nums = numbers;
	dp = new int[len][10][10];
	for (int i = 0; i < len; i++) {
		for (int j = 0; j < 10; j++) {
			Arrays.fill(dp[i][j], -1);
		}
	}
	return solve(0, 4, 6);
}

private int solve(int idx, int left, int right) {
	if (idx == len) {
		return 0;
	}

	if (dp[idx][left][right] != -1) {
		return dp[idx][left][right];
	}

	int num = nums.charAt(idx) - '0';
	int ans = Integer.MAX_VALUE;

	if (num != right) {
		ans = Math.min(solve(idx + 1, num, right) + cost[left][num], ans);
	}

	if (num != left) {
		ans = Math.min(solve(idx + 1, left, num) + cost[right][num], ans);
	}
	dp[idx][left][right] = ans;
	return ans;
}

private void initializeCost() {
	cost = new int[10][10];
	int r1;
	int c1;
	int r2;
	int c2;

	for (int i = 0; i < 10; i++) {
		for (int j = 0; j < 10; j++) {
			if (i == j) {
				cost[i][j] = 1;
				continue;
			}

			r1 = 3;
			c1 = 1;
			r2 = 3;
			c2 = 1;
			cost[i][j] = 2;

			if (i != 0) {
				r1 = (i - 1) / 3;
				c1 = (i - 1) % 3;
			}
			if (j != 0) {
				r2 = (j - 1) / 3;
				c2 = (j - 1) % 3;
			}

			int dr = Math.abs(r1 - r2);
			int dc = Math.abs(c1 - c2);
			int min = Math.min(dr, dc);
			int max = Math.max(dr, dc);
			int diff = dr + dc;

			if (diff > 1) {
				cost[i][j] = min * 3 + (max - min) * 2;
			}
		}
	}
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/136797