Medium
You are given an m x n
matrix grid
consisting of positive integers. You can move from a cell in the matrix to any other cell that is either to the bottom or to the right (not necessarily adjacent). The score of a move from a cell with the value c1
to a cell with the value c2
is c2 - c1
.
You can start at any cell, and you have to make at least one move.
Return the maximum total score you can achieve.
Example 1:
Input: grid = [[9,5,7,3],[8,9,6,1],[6,7,14,3],[2,5,3,1]]
Output: 9
Explanation: We start at the cell (0, 1)
, and we perform the following moves:
Move from the cell (0, 1)
to (2, 1)
with a score of 7 - 5 = 2
.
Move from the cell (2, 1)
to (2, 2)
with a score of 14 - 7 = 7
.
The total score is 2 + 7 = 9
.
Example 2:
Input: grid = [[4,3,2],[3,2,1]]
Output: -1
Explanation: We start at the cell (0, 0)
, and we perform one move: (0, 0)
to (0, 1)
. The score is 3 - 4 = -1
.
Constraints:
m == grid.length
n == grid[i].length
2 <= m, n <= 1000
4 <= m * n <= 105
1 <= grid[i][j] <= 105
import kotlin.math.max
class Solution {
fun maxScore(grid: List<List<Int>>): Int {
val m = grid.size - 1
var row = grid[m]
var n = row.size
val maxRB = IntArray(n--)
maxRB[n] = row[n]
var mx = maxRB[n]
var result = Int.MIN_VALUE
for (i in n - 1 downTo 0) {
val x = row[i]
result = max(result, (mx - x))
mx = max(mx, x)
maxRB[i] = mx
}
for (i in m - 1 downTo 0) {
row = grid[i]
mx = 0
for (j in n downTo 0) {
mx = max(mx, maxRB[j])
val x = row[j]
result = max(result, (mx - x))
mx = max(mx, x)
maxRB[j] = mx
}
}
return result
}
}