230317 지형 편집

public static long solution(int[][] land, int P, int Q) {
    long answer = -1;
    long maxHeight = 0;
    long minHeight = Long.MAX_VALUE;

    for (int i = 0; i < land.length; i++) {
        for (int j = 0; j < land[i].length; j++) {
            maxHeight = Math.max(maxHeight, land[i][j]);
            minHeight = Math.min(minHeight, land[i][j]);
        }
    }

    long front = minHeight;
    long rear = maxHeight;
    while (front <= rear) {
        long mid = (front + rear) / 2;

        long cost1 = getCost(land, mid, P, Q);
        long cost2 = getCost(land, mid + 1, P, Q);

        if (cost1 <= cost2) {
            answer = cost1;
            rear = mid - 1;
        } else {
            answer = cost2;
            front = mid + 1;
        }
    }

    return answer;
}

private static long getCost(int[][] land, long height, int P, int Q) {
    long cost = 0;
    for (int i = 0; i < land.length; i++) {
        for (int j = 0; j < land[i].length; j++) {
            if (land[i][j] < height) {
                cost += (height - land[i][j]) * P;
            } else if (land[i][j] > height) {
                cost += (land[i][j] - height) * Q;
            }
        }
    }

    return cost;
}