231030 파괴되지 않은 건물

public int solution(int[][] board, int[][] skill) {
	int n = board.length;
	int m = board[0].length;

	int[][] sum = calculateSkillSum(n, m, skill);

	return updateBoardAndGetCount(board, sum, n, m);
}

private int[][] calculateSkillSum(int n, int m, int[][] skill) {
	int[][] sum = new int[n + 1][m + 1];

	for (int[] s : skill) {
		int y1 = s[1];
		int x1 = s[2];
		int y2 = s[3];
		int x2 = s[4];
		int durability = (s[0] == 1 ? -s[5] : s[5]);

		sum[y1][x1] += durability;
		sum[y1][x2 + 1] += (-durability);
		sum[y2 + 1][x1] += (-durability);
		sum[y2 + 1][x2 + 1] += durability;
	}

	return sum;
}

private int updateBoardAndGetCount(int[][] board, int[][] sum, int n, int m) {
	for (int y = 1; y < n; y++) {
		for (int x = 0; x < m; x++) {
			sum[y][x] += sum[y - 1][x];
		}
	}

	for (int x = 1; x < m; x++) {
		for (int y = 0; y < n; y++) {
			sum[y][x] += sum[y][x - 1];
		}
	}

	int answer = 0;

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			board[i][j] += sum[i][j];
			if (board[i][j] > 0) {
				answer++;
			}
		}
	}

	return answer;
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/92344