43 lines
1.4 KiB
Go
43 lines
1.4 KiB
Go
// File: subset_sum_i.go
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// Created Time: 2023-06-24
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// Author: Reanon (793584285@qq.com)
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package chapter_backtracking
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import "sort"
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/* Backtracking algorithm: Subset Sum I */
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func backtrackSubsetSumI(start, target int, state, choices *[]int, res *[][]int) {
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// When the subset sum equals target, record the solution
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if target == 0 {
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newState := append([]int{}, *state...)
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*res = append(*res, newState)
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return
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}
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// Traverse all choices
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// Pruning two: start traversing from start to avoid generating duplicate subsets
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for i := start; i < len(*choices); i++ {
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// Pruning one: if the subset sum exceeds target, end the loop immediately
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// This is because the array is sorted, and later elements are larger, so the subset sum will definitely exceed target
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if target-(*choices)[i] < 0 {
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break
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}
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// Attempt: make a choice, update target, start
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*state = append(*state, (*choices)[i])
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// Proceed to the next round of selection
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backtrackSubsetSumI(i, target-(*choices)[i], state, choices, res)
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// Retract: undo the choice, restore to the previous state
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*state = (*state)[:len(*state)-1]
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}
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}
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/* Solve Subset Sum I */
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func subsetSumI(nums []int, target int) [][]int {
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state := make([]int, 0) // State (subset)
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sort.Ints(nums) // Sort nums
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start := 0 // Start point for traversal
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res := make([][]int, 0) // Result list (subset list)
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backtrackSubsetSumI(start, target, &state, &nums, &res)
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return res
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}
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