68 lines
1.9 KiB
Swift
68 lines
1.9 KiB
Swift
/**
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* File: coin_change_ii.swift
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* Created Time: 2023-07-16
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* Coin change II: Dynamic programming */
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func coinChangeIIDP(coins: [Int], amt: Int) -> Int {
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let n = coins.count
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// Initialize dp table
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var dp = Array(repeating: Array(repeating: 0, count: amt + 1), count: n + 1)
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// Initialize first column
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for i in 0 ... n {
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dp[i][0] = 1
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}
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// State transition
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for i in 1 ... n {
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for a in 1 ... amt {
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if coins[i - 1] > a {
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// If exceeding the target amount, do not choose coin i
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dp[i][a] = dp[i - 1][a]
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} else {
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// The sum of the two options of not choosing and choosing coin i
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dp[i][a] = dp[i - 1][a] + dp[i][a - coins[i - 1]]
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}
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}
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}
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return dp[n][amt]
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}
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/* Coin change II: Space-optimized dynamic programming */
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func coinChangeIIDPComp(coins: [Int], amt: Int) -> Int {
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let n = coins.count
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// Initialize dp table
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var dp = Array(repeating: 0, count: amt + 1)
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dp[0] = 1
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// State transition
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for i in 1 ... n {
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for a in 1 ... amt {
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if coins[i - 1] > a {
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// If exceeding the target amount, do not choose coin i
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dp[a] = dp[a]
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} else {
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// The sum of the two options of not choosing and choosing coin i
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dp[a] = dp[a] + dp[a - coins[i - 1]]
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}
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}
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}
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return dp[amt]
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}
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@main
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enum CoinChangeII {
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/* Driver Code */
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static func main() {
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let coins = [1, 2, 5]
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let amt = 5
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// Dynamic programming
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var res = coinChangeIIDP(coins: coins, amt: amt)
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print("Number of coin combinations to make up the target amount = \(res)")
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// Space-optimized dynamic programming
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res = coinChangeIIDPComp(coins: coins, amt: amt)
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print("Number of coin combinations to make up the target amount = \(res)")
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}
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}
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