题解 | #矩阵元素查找#常规题，分类多了点

class Solution {
public:
    int binaryFind(vector<int> mat, int n, int x) {
        int line = mat.size();
        int start = 0, end = line;
        while(start <= end) {
            int mid = (start + end) / 2;
            if (mat[mid] == x) {
                return mid;
            } else if (mat[mid] < x) {
                start = mid + 1;
            } else {
                end = mid - 1;
            }
        }
        return -1;
    }
    vector<int> findElement(vector<vector<int> > mat, int n, int m, int x) {
        vector<int> ret;
        if (n == 0 && m == 0) {
            return ret;
        }
        if (n == 1) {
            vector<int> vec;
            for (int i = 0; i < mat[0].size(); i++) {
                vec.push_back(mat[0][i]);
            }
            int index = binaryFind(vec, m, x);
            ret.push_back(0);
            ret.push_back(index);
            return ret;
        }
        if (m == 1) {
            vector<int> vec;
            for (int i = 0; i < mat.size(); i++) {
                vec.push_back(mat[i][0]);
            }
            int index = binaryFind(vec, n, x);
            ret.push_back(index);
            ret.push_back(0);
            return ret;
        }
        int columnIndex = 0, lineIndex = m - 1;
        while(columnIndex < n && lineIndex >= 0) {
            if (x == mat[columnIndex][lineIndex]) {
                ret.push_back(columnIndex);
                ret.push_back(lineIndex);
                return ret;
            } else if (x < mat[columnIndex][lineIndex]){
                lineIndex--;
                
            } else {
                columnIndex++;
            }
        }
        return ret;
        // write code here
    }
};