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Image Smoother
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Image Smoother
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/*
LeetCode 661:
Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 surrounding cells and itself. If a cell has less than 8 surrounding cells, then use as many as you can.
Example 1:
Input:
[[1,1,1],
[1,0,1],
[1,1,1]]
Output:
[[0, 0, 0],
[0, 0, 0],
[0, 0, 0]]
Explanation:
For the point (0,0), (0,2), (2,0), (2,2): floor(3/4) = floor(0.75) = 0
For the point (0,1), (1,0), (1,2), (2,1): floor(5/6) = floor(0.83333333) = 0
For the point (1,1): floor(8/9) = floor(0.88888889) = 0
Note:
The value in the given matrix is in the range of [0, 255].
The length and width of the given matrix are in the range of [1, 150].
Solution:
Laguage: C++
Tag:
*/
class Solution {
public:
vector<vector<int>> imageSmoother(vector<vector<int>>& M) {
// 1. O(8mn) time + O(mn) space
int trans[8][2] = {{0, -1}, {0, 1}, {-1, 0}, {1, 0}, {-1, -1}, {-1, 1}, {1, -1}, {1, 1}};
int rowSize = M.size(), colSize = M[0].size();
vector<vector<int>> res(rowSize, vector<int>(colSize, 0));
for (int i = 0; i < rowSize; ++i) {
for (int j = 0; j < colSize; ++j) {
int num = 1, count = M[i][j];
for (int k = 0; k < 8; ++k) {
int row = i + trans[k][0];
int col = j + trans[k][1];
if (!inbound(row, col, rowSize, colSize)) {
continue;
}
++num;
count += M[row][col];
}
res[i][j] = count / num;
}
}
return res;
}
bool inbound(int row, int col, int rowSize, int colSize) {
if (row >= 0 && row <rowSize && col >= 0 && col < colSize) {
return true;
}
return false;
}
};