Search a 2D Matrix II

Desicription

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

  • Integers in each row are sorted in ascending from left to right.
  • Integers in each column are sorted in ascending from top to bottom.

Example:

Consider the following matrix:

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[
  [1,   4,  7, 11, 15],
  [2,   5,  8, 12, 19],
  [3,   6,  9, 16, 22],
  [10, 13, 14, 17, 24],
  [18, 21, 23, 26, 30]
]

Given target = 5, return true.

Given target = 20, return false.

Solution

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class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int row = matrix.size();
        if(row == 0) {
            return false;
        }
        int col = matrix[0].size();
        if(col == 0) {
            return false;
        }
        int currentRow = 0;
        int currentCol = col - 1;
        while(true) {
            if(currentRow >= row || currentCol < 0) {
                return false;
            }
            auto current = matrix[currentRow][currentCol];
            if(target == current) {
                return true;
            }
            else if(target < current) {
                currentCol--;
            }
            else if(target > current) {
                currentRow++;
            }
        }
        return false;
    }
};