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55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
"""
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File: unbounded_knapsack.py
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Created Time: 2023-07-10
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Author: krahets (krahets@163.com)
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"""
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def unbounded_knapsack_dp(wgt: list[int], val: list[int], cap: int) -> int:
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"""Complete knapsack: Dynamic programming"""
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n = len(wgt)
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# Initialize dp table
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dp = [[0] * (cap + 1) for _ in range(n + 1)]
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# State transition
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for i in range(1, n + 1):
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for c in range(1, cap + 1):
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if wgt[i - 1] > c:
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# If exceeding the knapsack capacity, do not choose item i
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dp[i][c] = dp[i - 1][c]
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else:
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# The greater value between not choosing and choosing item i
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dp[i][c] = max(dp[i - 1][c], dp[i][c - wgt[i - 1]] + val[i - 1])
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return dp[n][cap]
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def unbounded_knapsack_dp_comp(wgt: list[int], val: list[int], cap: int) -> int:
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"""Complete knapsack: Space-optimized dynamic programming"""
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n = len(wgt)
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# Initialize dp table
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dp = [0] * (cap + 1)
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# State transition
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for i in range(1, n + 1):
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# Traverse in order
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for c in range(1, cap + 1):
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if wgt[i - 1] > c:
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# If exceeding the knapsack capacity, do not choose item i
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dp[c] = dp[c]
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else:
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# The greater value between not choosing and choosing item i
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dp[c] = max(dp[c], dp[c - wgt[i - 1]] + val[i - 1])
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return dp[cap]
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"""Driver Code"""
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if __name__ == "__main__":
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wgt = [1, 2, 3]
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val = [5, 11, 15]
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cap = 4
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# Dynamic programming
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res = unbounded_knapsack_dp(wgt, val, cap)
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print(f"The maximum item value without exceeding knapsack capacity is {res}")
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# Space-optimized dynamic programming
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res = unbounded_knapsack_dp_comp(wgt, val, cap)
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print(f"The maximum item value without exceeding knapsack capacity is {res}")
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