Sure, I'll help you write a test case generator for the "Range Update Query (RUQ)" problem. Here’s the code:

```python
import random

def tcgen():
    # Constraints
    MAX_N = 100000
    MAX_Q = 100000
    MAX_X = 2**31 - 1

    # Generate random n and q within the constraints
    n = random.randint(1, MAX_N)
    q = random.randint(1, MAX_Q)

    # Initialize list of queries
    queries = []

    for _ in range(q):
        query_type = random.choice([0, 1])
        if query_type == 0:
            s = random.randint(0, n - 1)
            t = random.randint(s, n - 1)
            x = random.randint(0, MAX_X)
            queries.append(f"0 {s} {t} {x}")
        else:
            i = random.randint(0, n - 1)
            queries.append(f"1 {i}")

    # First line is n and q
    input_data = f"{n} {q}\n" + "\n".join(queries)
    return input_data

# Example usage:
print(tcgen())
```

### Explanation:
1. **Constraints Definitions**:
    - `MAX_N` is the maximum number of elements in the sequence `A`.
    - `MAX_Q` is the maximum number of queries.
    - `MAX_X` is the maximum value for `x`, which is \(2^{31} - 1\).

2. **Random Generators**:
    - `n` is randomly chosen between 1 and `MAX_N`.
    - `q` is randomly chosen between 1 and `MAX_Q`.

3. **Query Generation**:
    - For each query, randomly decide the query type (`0` for update and `1` for find).
    - If the query is `0`, randomly generate `s`, `t`, and `x` according to the constraints.
    - If the query is `1`, randomly generate `i` according to the constraints.

4. **Output Formatting**:
    - The first line contains `n` and `q`.
    - The following lines are the generated queries.

The `tcgen` function returns a string representing the input data of the problem. You can use this function to generate various test cases for your competitive programming problem.