94 lines
968 B
Text
94 lines
968 B
Text
A. Alternating Sum of Numbers
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time limit per test
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2 seconds
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memory limit per test
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256 megabytes
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input
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standard input
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output
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standard output
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You are given a sequence of integers. Output the alternating sum of this sequence. In other words, output a1−a2+a3−a4+a5−…
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a
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1
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−
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a
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2
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+
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a
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3
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−
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a
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4
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+
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a
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5
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−
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…
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. That is, the signs of plus and minus alternate, starting with a plus.
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Input
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The first line of the test contains one integer t
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t
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(1≤t≤1000
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1
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≤
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t
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≤
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1000
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) — the number of test cases. Then follow t
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t
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test cases.
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The first line of each test case contains one integer n
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n
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(1≤n≤50
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1
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≤
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n
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≤
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50
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) — the length of the sequence. The second line of the test case contains n
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n
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integers a1,a2,…,an
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a
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1
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,
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a
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2
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,
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…
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,
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a
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n
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(1≤ai≤100
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1
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≤
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a
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i
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≤
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100
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).
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Output
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Output t
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t
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lines. For each test case, output the required alternating sum of the numbers.
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Example
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Input
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Copy
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4
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4
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1 2 3 17
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1
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100
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2
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100 100
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5
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3 1 4 1 5
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Output
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Copy
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-15
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100
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0
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10
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