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37 lines
943 B
37 lines
943 B
package rands |
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import ( |
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"math/rand/v2" |
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"time" |
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) |
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var ( |
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rad = rand.New(rand.NewPCG(uint64(time.Now().Unix()), uint64(time.Now().UnixNano()))) |
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) |
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// Choice 一个选项包含一个泛型项以及一个权重，该权重用于控制其被选中的频率 |
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type Choice[W int | int32 | int64, T any] struct { |
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Weight W |
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Item T |
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} |
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// WeightedChoice 加权随机选择, 从所提供的选项中返回一个选项, 权重值为 0 的选项永远不会被选中 |
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// Based on this algorithm: http://eli.thegreenplace.net/2010/01/22/weighted-random-generation-in-python/ |
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func WeightedChoice[W int | int32 | int64, T any](choices []Choice[W, T], rd ...*rand.Rand) (ret Choice[W, T], ok bool) { |
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sum := int64(0) |
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for _, c := range choices { |
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sum += int64(c.Weight) |
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} |
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crd := rad |
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if len(rd) > 0 && rd[0] != nil { |
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crd = rd[0] |
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} |
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r := crd.Int64N(sum) |
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for _, c := range choices { |
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r -= int64(c.Weight) |
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if r < 0 { |
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return c, true |
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} |
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} |
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return |
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}
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