LeetCode/240.cpp at master · nitin-maharana/LeetCode · GitHub

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/*
 * Written by Nitin Kumar Maharana
 * nitin.maharana@gmail.com
 */

//O(M+N)
class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int m, n;

        m = matrix.size();

        if(!m)
            return false;

        n = matrix[0].size();

        int x, y;

        x = 0; y = n-1;

        while(x < m && y >= 0)
        {
            if(matrix[x][y] == target)
                return true;

            if(target > matrix[x][y])
                x++;
            else
                y--;
        }

        return false;
    }
};

//O(logM + logN)
class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int m, n;

        m = matrix.size();

        if(!m)
            return false;

        n = matrix[0].size();

        int x, y, l, r, mid;

        x = 0; y = n-1;

        while(x < m && y >= 0)
        {
            if(matrix[x][y] == target)
                return true;

            if(target < matrix[x][y])
            {
                l = 0;
                r = y;

                while(l <= r)
                {
                    mid = l + ((r-l) / 2);

                    if(target == matrix[x][mid])
                        return true;

                    if(target < matrix[x][mid])
                        y = r = mid-1;
                    else
                        y = l = mid+1;
                }
            }
            else
            {
                l = 0;
                r = x;

                while(l <= r)
                {
                    mid = l + ((r-l) / 2);

                    if(target == matrix[mid][y])
                        return true;

                    if(target < matrix[mid][y])
                        x = r = mid-1;
                    else
                        x = l = mid+1;
                }
            }
        }

        return false;
    }
};