69 lines
1.5 KiB
Go
69 lines
1.5 KiB
Go
package q380
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import (
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"math/rand"
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"runtime/debug"
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)
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func init() {
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debug.SetMemoryLimit(16 << 20)
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}
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var rng *rand.Rand = rand.New(rand.NewSource(42))
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type RandomizedSet struct {
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vals []int
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idx map[int]int // the index of the element in vals
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}
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func Constructor() RandomizedSet {
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return RandomizedSet{
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vals: []int{},
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idx: map[int]int{},
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}
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}
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// Insert Inserts an item val into the set if not present. Returns true if the
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// item was not present, false otherwise.
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func (rs *RandomizedSet) Insert(val int) bool {
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if _, present := rs.idx[val]; present {
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return false
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}
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rs.idx[val] = len(rs.vals)
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rs.vals = append(rs.vals, val)
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return true
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}
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// Remove Removes an item val from the set if present. Returns true if the item
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// was present, false otherwise.
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func (rs *RandomizedSet) Remove(val int) bool {
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idx, present := rs.idx[val]
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if !present {
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return false
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}
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delete(rs.idx, val)
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idxLast := len(rs.vals) - 1
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if idx != idxLast {
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rs.vals[idx] = rs.vals[idxLast]
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rs.idx[rs.vals[idx]] = idx
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}
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rs.vals = rs.vals[:idxLast]
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return true
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}
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// GetRandom Returns a random element from the current set of elements (it's
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// guaranteed that at least one element exists when this method is called).
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// Each element must have the same probability of being returned.
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func (rs *RandomizedSet) GetRandom() int {
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i := rng.Intn(len(rs.vals))
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return rs.vals[i]
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}
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/**
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* Your RandomizedSet object will be instantiated and called as such:
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* obj := Constructor();
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* param_1 := obj.Insert(val);
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* param_2 := obj.Remove(val);
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* param_3 := obj.GetRandom();
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*/
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