37 lines
922 B
Go
37 lines
922 B
Go
// File: climbing_stairs_backtrack.go
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// Created Time: 2023-07-18
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// Author: Reanon (793584285@qq.com)
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package chapter_dynamic_programming
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/* Backtracking */
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func backtrack(choices []int, state, n int, res []int) {
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// When climbing to the nth step, add 1 to the number of solutions
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if state == n {
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res[0] = res[0] + 1
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}
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// Traverse all choices
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for _, choice := range choices {
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// Pruning: do not allow climbing beyond the nth step
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if state+choice > n {
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continue
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}
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// Attempt: make a choice, update the state
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backtrack(choices, state+choice, n, res)
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// Retract
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}
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}
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/* Climbing stairs: Backtracking */
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func climbingStairsBacktrack(n int) int {
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// Can choose to climb up 1 step or 2 steps
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choices := []int{1, 2}
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// Start climbing from the 0th step
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state := 0
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res := make([]int, 1)
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// Use res[0] to record the number of solutions
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res[0] = 0
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backtrack(choices, state, n, res)
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return res[0]
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}
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