Problem C. Minimum Path in Triangle
The key to the solution is forming all possible minimum-cost paths from top to bottom row. You can not be sure which one will have minimum cost, so let's traverse a triangle
and update values in the cells:
triangle[i][j] += min(triangle[i-1][j-1], triangle[i-1][j]
: thats how you can reach cell
[i, j]` with min costtriangle[i][0] += triangle[i-1][0], triangle[i][i-1] += triangle[i-1][i-1]
: extreme cases (number of columns in each row is equal to number of row).
After updating, choose the minimum path cost, which is in the last row.
1234567891011121314151617181920def minPath(triangle): for i in range(1, len(triangle)): for j in range(i+1): small = 10000000 if j > 0: small = triangle[i-1][j-1] if j < i: small = min(small, triangle[i-1][j]) triangle[i][j] += small return min(triangle[-1]) triangle = [[90], [72, 6], [3, 61, 51], [90, 70, 23, 100], [79, 92, 72, 14, 1], [7, 97, 29, 100, 93, 93], [52, 95, 21, 36, 69, 69, 14], [33, 82, 20, 37, 79, 83, 21, 45]] print(minPath(triangle))
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SectionΒ 3. ChapterΒ 3
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Problem C. Minimum Path in Triangle
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The key to the solution is forming all possible minimum-cost paths from top to bottom row. You can not be sure which one will have minimum cost, so let's traverse a triangle
and update values in the cells:
triangle[i][j] += min(triangle[i-1][j-1], triangle[i-1][j]
: thats how you can reach cell
[i, j]` with min costtriangle[i][0] += triangle[i-1][0], triangle[i][i-1] += triangle[i-1][i-1]
: extreme cases (number of columns in each row is equal to number of row).
After updating, choose the minimum path cost, which is in the last row.
1234567891011121314151617181920def minPath(triangle): for i in range(1, len(triangle)): for j in range(i+1): small = 10000000 if j > 0: small = triangle[i-1][j-1] if j < i: small = min(small, triangle[i-1][j]) triangle[i][j] += small return min(triangle[-1]) triangle = [[90], [72, 6], [3, 61, 51], [90, 70, 23, 100], [79, 92, 72, 14, 1], [7, 97, 29, 100, 93, 93], [52, 95, 21, 36, 69, 69, 14], [33, 82, 20, 37, 79, 83, 21, 45]] print(minPath(triangle))
Everything was clear?
Thanks for your feedback!
Awesome!
Completion rate improved to 8.33SectionΒ 3. ChapterΒ 3
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