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construct-product-matrix.py
44 lines (41 loc) · 1.5 KB
/
construct-product-matrix.py
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# Time: O(m * n)
# Space: O(m * n)
# prefix sum
class Solution(object):
def constructProductMatrix(self, grid):
"""
:type grid: List[List[int]]
:rtype: List[List[int]]
"""
MOD = 12345
right = [1]*(len(grid)*len(grid[0])+1)
for i in reversed(xrange(len(grid))):
for j in reversed(xrange(len(grid[0]))):
right[i*len(grid[0])+j] = (right[(i*len(grid[0])+j)+1]*grid[i][j])%MOD
left = 1
for i in xrange(len(grid)):
for j in xrange(len(grid[0])):
grid[i][j], left = (left*right[(i*len(grid[0])+j)+1])%MOD, (left*grid[i][j])%MOD
return grid
# Time: O(m * n)
# Space: O(m * n)
# prefix sum
class Solution2(object):
def constructProductMatrix(self, grid):
"""
:type grid: List[List[int]]
:rtype: List[List[int]]
"""
MOD = 12345
left = [1]*(len(grid)*len(grid[0])+1)
for i in xrange(len(grid)):
for j in xrange(len(grid[0])):
left[(i*len(grid[0])+j)+1] = (left[i*len(grid[0])+j]*grid[i][j])%MOD
right = [1]*(len(grid)*len(grid[0])+1)
for i in reversed(xrange(len(grid))):
for j in reversed(xrange(len(grid[0]))):
right[i*len(grid[0])+j] = (right[(i*len(grid[0])+j)+1]*grid[i][j])%MOD
for i in xrange(len(grid)):
for j in xrange(len(grid[0])):
grid[i][j] = (left[i*len(grid[0])+j]*right[(i*len(grid[0])+j)+1])%MOD
return grid