[INSTRUCTIONS]

You are a program-analysis assistant. Perform a **static** data-dependence analysis on a given code snippet, treating each branch or loop condition as potentially taking any outcome, without using semantic or symbolic execution to prune paths.


## 1. Data Dependence Definition

   Data dependence captures the influence of data flow between variables.

   We denote each variable instance as `(var,lineNumber)`, meaning the variable `var` defined or updated at `lineNumber`.

   >  **Direct Data Dependence**
   A variable instance `(varB,lineB)` is **directly** data-dependent on `(varA,lineA)` if `lineA` writes to `varA`. Then, without overwritting the value of `varA`, `lineB` reads `varA` and compute the value of `varB`. In other words, the value of `(varB,lineB)` relies on the value produced at `(varA,lineA)`. In addition, changing the execution order of `(varA,lineA)` and `(varB,lineB)` would alter their results.


   A variable instance `(varB,lineB)` is data-dependent on `(varA,lineA)` if there is a **transitive** (indirect) chain of **direct** data dependencies from `(varA,lineA)` to `(varB,lineB)`. This is equivalent to saying that `(varA,lineA)` has data dependence over `(varB,lineB)`, meaning the value written at `(varA,lineA)` can propagate to `(varB,lineB)` through a sequence of read/write operations.


## 2. Output Format
   When asked "Which variable instances have data dependence over `(targetVar, targetLine)`? List all such variables.", respond:
   ```json
   {
    "DataDependenceSources": [
      ["valA", lineA],
      ["valB", lineB],
      ...
    ]
   }
   ```

  If you believe there is no variables have data dependence over `(targetVar, targetLine)`, respond:
   ```json
   {
    "DataDependenceSources": []
   }
   ```
  

## 3. Intraprocedural Data Dependence
   All dependence analysis is performed within **a single function**. We do not track dependencies across function boundaries. The analysis only applies to variables and control structures inside the **specified function**.

## 4. Example Code Snippet

### Example 1

```python
1    total = 0
2    value = 1
3    step = value
4    if step > 1:
5        value += 3
6    while total <= 10:
7        total += value
8        difference = total - step
9        step += 1
10   final_result = total * 2
```


#### Example Question 1.1:
Which variable instances have data dependence over `(step,9)`? List all such variables.


**Analysis**:
- Line 9: `step += 1`, meaning `(step,9)` is directly data-dependent on `(step,3)` (or `(step,9)` itself) because step is updated based on its previous value.
- Line 3: `step = value`, meaning `(step,3)` is directly data-dependent on `(value,2)`.
Therefore, there exists a transitive data dependence chain from `(value,2)` to `(step,9)` through `(step,3)`. 


**Output**:
```json
   {
    "DataDependenceSources": [
      ["step", 9],
      ["step", 3],
      ["value", 2],
    ]
   }
```





#### Example Question 1.2 
Which variable instances have data dependence over `(total,7)`? List all such variables.


**Analysis**:
- Line 7: `total += value`, meaning `(total,7)` reads from `total` at line 1 or 7 (itself), and `value` from either `(value,2)` or `(value,5)`.
- Line 5: `value` is updated in `value += 3`, meaning `(value,5)` depends on `(value,2)` (or `(value,5)` itself). However, this update is inside an if statement, which means it may or may not execute depending on runtime conditions.
- Line 2: value is initialized at `(value,2)`.


At this point, whether `(total,7)` depends on `(value,5)` depends on whether line 4 (`if step>1`) is `true`. Since this is a static analysis, all possible paths are considered without analyzing actual reachability. This means line 5 is treated as both possibly executed and possibly not executed.

- If line 4 evaluates to `true`, `(total,7)` depends on `(value,5)`, forming the trace: `(value,2) -> (value,5) -> (total,7)`. 
- If line 4 evaluates to `false`, `(total,7)` directly depends on `(value,2)`, forming the trace: `(value,2) -> (total,7)`



**Output**:
```json
   {
    "DataDependenceSources": [
      ["total", 1],
      ["total", 7],
      ["value", 5],
      ["value", 2]
    ]
   }
```



### Example 2

```python
1    arr = [1, 2, 3]
2    x = 5
3    if x > 2:
4        arr[0] = x   
5    for i in range(3):
6        arr[i] += 1  
7        temp = arr[i]  
8        y = temp + 1  
9    result = arr[-1]
```

#### Example Question 2.1:
Which variable instances have data dependence over `(arr,6)`? List all such variables.



**Analysis**
- Line 6: `arr[i] += 1` modifies `arr[i]`, but i varies during the loop execution.
   - If `i == 0`, `arr[i]` refers to `arr[0]`, which was updated in line 4 (or line 6 itself), establishing a dependence chain `(arr,4)` -> `(arr,6)`.
   - If `i != 0`, `arr[i]` does not refer to `arr[0]`, meaning it depend on `(arr,1)` (or `(arr,6)` itself), not `(arr,4)`.
   - However, since static analysis considers all possible paths without resolving i’s runtime value, we must assume `arr[i]` could be `arr[0]`, leading to a possible dependence.
- Line 4: `arr[0] = x`, meaning `(arr,4)` depends on `(x,2)`.
- Line 2: `x` is initialized at `(x,2)`.




**Output**:
```json
   {
    "DataDependenceSources": [
      ["arr", 6],
      ["arr", 4],
      ["arr", 1],
      ["i", 5],
      ["x", 2]
    ]
   }
```


#### Example Question 2.2:
Which variable instances have data dependence over `(temp,7)`? List all such variables.


**Analysis**:
- Line 7: `temp = arr[i]`, meaning temp depends on `i`, since `i` determines which element of arr is accessed. And `arr[i]` can only refer to `(arr,6)` as they have the same index.
- Line 5: `i` is initialized and iterates over the range 0 to 3.


**Output**:
```json
   {
    "DataDependenceSources": [
      ["arr", 6],
      ["i", 5],
    ]
   }
```

#### Example Question 2.3:
Which variable instances have data dependence over `(result,9)`? List all such variables.

**Analysis**:
- Line 9: `result = arr[-1]`, meaning result depends on `arr[-1]`, which is arr[2], possibly get updated at line 6 (or line 1).
  - If it is from line 6: `arr[i] += 1`, `arr[i]` is modified based on the value of `i`. Line 5: `i` iterates over 0 to 3.
  - If it is from line 1: `arr = [1, 2, 3]`, it is initialized at line 1 without any other data dependencies.

**Output**:
```json
   {
    "DataDependenceSources": [
      ["arr", 6],
      ["arr", 1],
      ["i", 5],
    ]
   }
```

---

[YOUR TURN]

Below is **your target snippet**. 

```Java
1   import java.util.*;
2   public class Main {
3   	public static boolean bfs (int sx,int sy, int[] spx, int[] spy) {
4   		int size = 10, spCnt = 0;
5   		int[] dx = {-1,0,1,-1,0,1,-2,-2,-2,2,2,2};
6   		int[] dy = {-2,-2,-2,2,2,2,-1,0,1,-1,0,1};
7   		int[] dx2 = {0,0,1,1,1,0,-1,-1,-1};
8   		int[] dy2 = {0,-1,-1,0,1,1,1,0,-1,-1};
9   		boolean[][] park = new boolean[size][size];
10  		Queue<Integer> queueX = new LinkedList<Integer>();
11  		Queue<Integer> queueY = new LinkedList<Integer>();
12  		queueX.add(sx);
13  		queueY.add(sy);
14  		while (!queueX.isEmpty()) {
15  			if (spCnt == spx.length) {
16  				return true;
17  			}
18  			for (int i = 0; i < dx2.length; i++) {
19  				int y = spy[spCnt] + dy2[i];
20  				int x = spx[spCnt] + dx2[i];
21  				if (0 <= y && y < size &&
22  					0 <= x && x < size) {
23  					park[y][x] = true;
24  				}
25  			}
26  			Queue<Integer> nx = new LinkedList<Integer>();
27  			Queue<Integer> ny = new LinkedList<Integer>();
28  			while (!queueX.isEmpty()) {
29  				int x = queueX.poll();
30  				int y = queueY.poll();
31  				for (int i = 0; i < dx.length; i++) {
32  					int nextX = x + dx[i];
33  					int nextY = y + dy[i];
34  					if (0 <= nextX && nextX < 10 &&
35  						0 <= nextY && nextY < 10 &&
36  						park[nextY][nextX]) {
37  						nx.add(nextX);
38  						ny.add(nextY);
39  					}
40  				}
41  			}
42  			spCnt++;
43  			park = new boolean[size][size];
44  			queueX = nx;
45  			queueY = ny;
46  		}
47  		return false;
48  	}
49  	public static void main(String[] args) {
50  		Scanner sc = new Scanner(System.in);
51  		while (true) {
52  			int sx = sc.nextInt();
53  			int sy = sc.nextInt();
54  			if (sx == 0 && sy == 0) break;
55  			sc.nextLine();
56  			int n = sc.nextInt();
57  			int[] spx = new int[n];
58  			int[] spy = new int[n];
59  			sc.nextLine();
60  			for (int i = 0; i < n; i++) {
61  				spx[i] = sc.nextInt();
62  				spy[i] = sc.nextInt();
63  			}
64  			sc.nextLine();
65  			System.out.println(bfs(sx,sy,spx,spy) ? "OK" : "NA");
66  		}
67  	}
68  }
```


**Question**: Which variable instances have data dependence over `(i,18)` in function `bfs`? List all such variables.

**Output**:


Ground truth answer: no