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@@ -1,9 +1,29 @@
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package main
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-func maxProfit(prices []int) int {
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- return 0
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+func maxProfit(prices []int) (profit int) {
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+ if len(prices) <= 1 {
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+ return 0
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+ }
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+ K := 2
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+ dp := make([][]int, K+1) // For k transactions
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+ for i := range dp {
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+ dp[i] = make([]int, len(prices))
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+ }
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+ for k := 1; k <= K; k++ {
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+ tmpMax := dp[k-1][0] - prices[0]
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+ for i := 1; i < len(prices); i++ {
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+ // if not sell stock at day i, dp[k][i] = dp[k][i-1]
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+ // else, dp[k][i] = max(dp[k-1][j] + prices[i] - prices[j]), j in [0, i-1]
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+ // ie. dp[k][i] = prices[i] + max(dp[k-1][j] - prices[j]), j in [0, i-1]
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+ dp[k][i] = maxInt(dp[k][i-1], prices[i]+tmpMax)
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+ tmpMax = maxInt(tmpMax, dp[k-1][i]-prices[i])
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+ profit = maxInt(profit, dp[k][i])
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+ }
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+ }
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+ return
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}
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-func main() {
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-
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-}
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+// func main() {
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+// println(maxProfit([]int{3, 3, 5, 0, 0, 3, 1, 4}), 6)
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+// println(maxProfit([]int{1, 2, 3, 4, 5}), 4)
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+// }
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