Find row with maximum sum in a Matrix
Given an N*N matrix. The task is to find the index of a row with the maximum sum. That is the row whose sum of elements is maximum.
Examples:
Input : mat[][] = {
{ 1, 2, 3, 4, 5 },
{ 5, 3, 1, 4, 2 },
{ 5, 6, 7, 8, 9 },
{ 0, 6, 3, 4, 12 },
{ 9, 7, 12, 4, 3 },
};
Output : Row 3 has max sum 35
Input : mat[][] = {
{ 1, 2, 3 },
{ 4, 2, 1 },
{ 5, 6, 7 },
};
Output : Row 3 has max sum 18
The idea is to traverse the matrix row-wise and find the sum of elements in each row and check for every row if current sum is greater than the maximum sum obtained till the current row and update the maximum_sum accordingly.
Below is the implementation of the above approach:
C++
// C++ program to find row with // max sum in a matrix #include <bits/stdc++.h> using namespace std; #define N 5 // No of rows and column // Function to find the row with max sum pair<int, int> colMaxSum(int mat[N][N]) { // Variable to store index of row // with maximum int idx = -1; // Variable to store max sum int maxSum = INT_MIN; // Traverse matrix row wise for (int i = 0; i < N; i++) { int sum = 0; // calculate sum of row for (int j = 0; j < N; j++) { sum += mat[i][j]; } // Update maxSum if it is less than // current sum if (sum > maxSum) { maxSum = sum; // store index idx = i; } } pair<int, int> res; res = make_pair(idx, maxSum); // return result return res; } // Driver code int main() { int mat[N][N] = { { 1, 2, 3, 4, 5 }, { 5, 3, 1, 4, 2 }, { 5, 6, 7, 8, 9 }, { 0, 6, 3, 4, 12 }, { 9, 7, 12, 4, 3 }, }; pair<int, int> ans = colMaxSum(mat); cout << "Row " << ans.first + 1 << " has max sum " << ans.second; return 0; } |
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Java
// Java program to find row with // max sum in a matrix import java.util.ArrayList; class MaxSum { public static int N; static ArrayList<Integer> colMaxSum(int mat[][]) { // Variable to store index of row // with maximum int idx = -1; // Variable to store maximum sum int maxSum = Integer.MIN_VALUE; // Traverse the matrix row wise for (int i = 0; i < N; i++) { int sum = 0; for (int j = 0; j < N; j++) { sum += mat[i][j]; } // Update maxSum if it is less than // current row sum if (maxSum < sum) { maxSum = sum; // store index idx = i; } } // Arraylist to store values of index // of maximum sum and the maximum sum together ArrayList<Integer> res = new ArrayList<>(); res.add(idx); res.add(maxSum); return res; } // Driver code public static void main(String[] args) { N = 5; int[][] mat = { { 1, 2, 3, 4, 5 }, { 5, 3, 1, 4, 2 }, { 5, 6, 7, 8, 9 }, { 0, 6, 3, 4, 12 }, { 9, 7, 12, 4, 3 }, }; ArrayList<Integer> ans = colMaxSum(mat); System.out.println("Row "+ (ans.get(0)+1)+ " has max sum " + ans.get(1)); } } // This code is contributed by Vivekkumar Singh |
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Python3
# Python3 program to find row with # max sum in a matrix import sys N = 5 # No of rows and column # Function to find the row with max sum def colMaxSum(mat): # Variable to store index of row # with maximum idx = -1 # Variable to store max sum maxSum = -sys.maxsize # Traverse matrix row wise for i in range(0, N): sum = 0 # calculate sum of row for j in range(0, N): sum += mat[i][j] # Update maxSum if it is less than # current sum if (sum > maxSum): maxSum = sum # store index idx = i res = [idx, maxSum] # return result return res # Driver code mat = [[ 1, 2, 3, 4, 5], [ 5, 3, 1, 4, 2], [ 5, 6, 7, 8, 9], [ 0, 6, 3, 4, 12], [ 9, 7, 12, 4, 3]] ans = colMaxSum(mat) print("Row", ans[0] + 1, "has max sum", ans[1]) # This code is contributed by Sanjit_Prasad |
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C#
// C# program to find row with // max sum in a matrix using System; using System.Collections.Generic; public class MaxSum { public static int N; static List<int> colMaxSum(int [,]mat) { // Variable to store index of row // with maximum int idx = -1; // Variable to store maximum sum int maxSum = int.MinValue; // Traverse the matrix row wise for (int i = 0; i < N; i++) { int sum = 0; for (int j = 0; j < N; j++) { sum += mat[i, j]; } // Update maxSum if it is less than // current row sum if (maxSum < sum) { maxSum = sum; // store index idx = i; } } // Arraylist to store values of index // of maximum sum and the maximum sum together List<int> res = new List<int>(); res.Add(idx); res.Add(maxSum); return res; } // Driver code public static void Main(String[] args) { N = 5; int[,] mat = { { 1, 2, 3, 4, 5 }, { 5, 3, 1, 4, 2 }, { 5, 6, 7, 8, 9 }, { 0, 6, 3, 4, 12 }, { 9, 7, 12, 4, 3 }, }; List<int> ans = colMaxSum(mat); Console.WriteLine("Row "+ (ans[0]+1)+ " has max sum " + ans[1]); } } // This code has been contributed by 29AjayKumar |
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Output:
Row 3 has max sum 35
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