README_EN.md

1198. Find Smallest Common Element in All Rows

中文文档

Description

Given an m x n matrix mat where every row is sorted in strictly increasing order, return the smallest common element in all rows.

If there is no common element, return -1.

 

Example 1:

Input: mat = [[1,2,3,4,5],[2,4,5,8,10],[3,5,7,9,11],[1,3,5,7,9]]
Output: 5

Example 2:

Input: mat = [[1,2,3],[2,3,4],[2,3,5]]
Output: 2

 

Constraints:

• m == mat.length
• n == mat[i].length
• 1 <= m, n <= 500
• 1 <= mat[i][j] <= 104
• mat[i] is sorted in strictly increasing order.

Solutions

Python3

class Solution:
    def smallestCommonElement(self, mat: List[List[int]]) -> int:
        counter = Counter()
        for row in mat:
            for num in row:
                counter[num] += 1
                if counter[num] == len(mat):
                    return num
        return -1

Java

class Solution {
    public int smallestCommonElement(int[][] mat) {
        int[] counter = new int[10001];
        for (int[] row : mat) {
            for (int num : row) {
                ++counter[num];
                if (counter[num] == mat.length) {
                    return num;
                }
            }
        }
        return -1;
    }
}

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