Search a 2D Matrix II
LeetCode https://leetcode.cn/problems/search-a-2d-matrix-ii/
from bottom-left to up-right corner
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class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
return false;
}
int row = matrix.length - 1;
int col = 0;
while (row >= 0 && col < matrix[0].length) {
if (matrix[row][col] == target) {
return true;
} else if (matrix[row][col] > target) {
row--;
} else {
col++;
}
} // end while
return false;
}
}
from up-right to bottom-left corner
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class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
return false;
}
int row = 0;
int col = matrix[0].length - 1;
while (row <= matrix.length - 1 && col >= 0) {
if (matrix[row][col] < target) {
row++;
} else if (matrix[row][col] > target) {
col--;
} else {
return true;
}
}
return false;
}
}
Complexity
- Time = O(m+n)
- Space = O(1)
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