C++STL之numeric库用法

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vector<int> v = {1,2,3,4,5};
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int sum = accumulate(v.begin(), v.end(), 0);                    // 15
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int product = accumulate(v.begin(), v.end(), 1, multiplies<>()); // 120

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vector<int> a = {1,2,3}, b = {4,5,6};
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int dot = inner_product(a.begin(), a.end(), b.begin(), 0);      // 32
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int sum_abs_diff = inner_product(a.begin(), a.end(), b.begin(), 0, plus<>(),
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                                [](int x, int y){return abs(x-y);}); // 9

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vector<int> nums = {2,4,6,8};
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vector<int> diff(4);
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adjacent_difference(nums.begin(), nums.end(), diff.begin());    // [2,2,2,2]
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adjacent_difference(nums.begin(), nums.end(), diff.begin(), multiplies<>()); // [2,8,24,48]

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vector<int> nums = {1,2,3,4};
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vector<int> prefix(4);
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partial_sum(nums.begin(), nums.end(), prefix.begin());         // [1,3,6,10]
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partial_sum(nums.begin(), nums.end(), prefix.begin(), multiplies<>()); // [1,2,6,24]

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int a = 12, b = 18;
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int result = gcd(a, b);  // 6
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int result2 = gcd(48, 60); // 12

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int a = 12, b = 18;
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int result = lcm(a, b);  // 36
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int result2 = lcm(4, 6); // 12

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int x = 10, y = 20;
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int mid = midpoint(x, y);  // 15
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double dmid = midpoint(1.5, 3.5); // 2.5

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vector<int> data = {1,3,5};
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int total = accumulate(data.begin(), data.end(), 0);           // 9
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vector<int> pre(3), diff(3);
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partial_sum(data.begin(), data.end(), pre.begin());            // [1,4,9]
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adjacent_difference(data.begin(), data.end(), diff.begin());   // [1,2,2]