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18 lines
268 B
Python
18 lines
268 B
Python
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print("somme des n premiers entiers")
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n = int(input("entrez n : "))
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#@ assume n >= 0
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s = 0
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k = 0
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while k <= n:
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#@ invariant k <= n+1
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#@ invariant s == (k - 1) * k // 2
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#@ variant n - k
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s = s + k
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k = k + 1
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print(s)
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#@ assert s == n * (n+1) // 2
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