# LeetCode 1779. Find Nearest Point That Has the Same X or Y Coordinate

You are given two integers, `x` and `y`, which represent your current location on a Cartesian grid: `(x, y)`. You are also given an array `points` where each `points[i] = [ai, bi]` represents that a point exists at `(ai, bi)`. A point is **valid** if it shares the same x-coordinate or the same y-coordinate as your location.

Return *the index **(0-indexed)** of the **valid** point with the smallest **Manhattan distance** from your current location*. If there are multiple, return *the valid point with the **smallest** index*. If there are no valid points, return `-1`.

The **Manhattan distance** between two points `(x1, y1)` and `(x2, y2)` is `abs(x1 - x2) + abs(y1 - y2)`.

**Example 1:**

```
Input: x = 3, y = 4, points = [[1,2],[3,1],[2,4],[2,3],[4,4]]
Output: 2
Explanation: Of all the points, only [3,1], [2,4] and [4,4] are valid. Of the valid points, [2,4] and [4,4] have the smallest Manhattan distance from your current location, with a distance of 1. [2,4] has the smallest index, so return 2.
```

**Example 2:**

```
Input: x = 3, y = 4, points = [[3,4]]
Output: 0
Explanation: The answer is allowed to be on the same location as your current location.
```

**Example 3:**

```
Input: x = 3, y = 4, points = [[2,3]]
Output: -1
Explanation: There are no valid points.
```

**Constraints:**

* `1 <= points.length <= 10^4`
* `points[i].length == 2`
* `1 <= x, y, ai, bi <= 10^4`

## Solution:

```
class Solution {
public:
    int nearestValidPoint(int x, int y, vector<vector<int>>& points) {
        int index = -1;
        int distance = INT_MAX;
        
        for (int i = 0; i < points.size(); i++) {
            if (x == points[i][0] || y == points[i][1]) {
                int current_dis = abs(x - points[i][0]) + abs(y - points[i][1]);
                if (current_dis < distance) {
                    distance = current_dis;
                    index = i;
                }
            }
        }
        
        return index;
    }
};
```


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