Project Euler problem 82 asks:
The minimal path sum in the 5 by 5 matrix below, by starting in any cell in the left column and finishing in any cell in the right column, and only moving up, down, and right, is 201 → 96 → 342 → 234 → 103 → 18; the sum is equal to 994.
131 673 234 103 18 201 96 342 965 150 630 803 746 422 111 537 699 497 121 956 805 732 524 37 331Find the minimal path sum, in
matrix.txt(right click and 'Save Link/Target As...'), a 31K text file containing a 80 by 80 matrix, from the left column to the right column.
Here's my solution:
def main():
matrix = [
[131, 673, 234, 103, 18],
[201, 96, 342, 965, 150],
[630, 803, 746, 422, 111],
[537, 699, 497, 121, 956],
[805, 732, 524, 37, 331]
]
size = len(matrix)
best = [matrix[row][0] for row in range(size)]
for col in range(1, size):
column = [matrix[row][col] for row in range(size)]
tmp = column[:]
for i in range(size):
column[i] += best[i] # right
for j in range(0, i): # up
if sum([best[j]]+tmp[j:i+1]) < column[i]:
column[i] = sum([best[j]]+tmp[j:i+1])
for k in range(i, size): # bottom
if sum([best[k]] +tmp[i:k+1]) < column[i]:
column[i] = sum([best[k]] +tmp[i:k+1])
best = column
#print(best)
return min(best)
if __name__ == "__main__":
print(main())
Please advise how it can be improved.
