LintCode 炼码

class Solution {
public:
    /**
     * @param matrix: matrix, a list of lists of integers
     * @param target: An integer
     * @return: a boolean, indicate whether matrix contains target
     */
    bool searchMatrix(vector<vector<int>> &matrix, int target) {
        // write your code here
        if (matrix.size() <= 0 || matrix[0].size() <= 0) {
            return false;
        }
        int left = 0;
        int right = matrix.size() * matrix[0].size()-1;
        auto get_val = [&matrix](int index) {
            int row = index / matrix[0].size();
            int col = index % matrix[0].size();
            return matrix[row][col];
        };
        while (left + 1 < right) {
            int mid = left + (right-left)/2;
            if (get_val(mid) == target) {
                return true;
            } else if (get_val(mid) > target) {
                right = mid;
            } else {
                left = mid;
            }
        }
        if (get_val(left) == target) {
            return true;
        }
        if (get_val(right) == target) {
            return true;
        }
        return false;
    }
};