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