Create 188-best-time-to-buy-and-sell-stock-iv.js

Author: everthis

188-best-time-to-buy-and-sell-stock-iv.js

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+/**
+ * @param {number} k
+ * @param {number[]} prices
+ * @return {number}
+ */
+const maxProfit = function(k, prices) {
+  if (!prices.length) return 0
+  let len = prices.length,
+    res = 0
+  if (k >= ~~(len / 2)) {
+    for (let i = 1; i < len; i++) {
+      res += Math.max(prices[i] - prices[i - 1], 0)
+    }
+    return res
+  }
+  const buy = new Array(k + 1).fill(Number.MIN_SAFE_INTEGER)
+  const sell = new Array(k + 1).fill(0)
+
+  for (let p of prices) {
+    for (let i = 1; i <= k; i++) {
+      buy[i] = Math.max(sell[i - 1] - p, buy[i])
+      sell[i] = Math.max(buy[i] + p, sell[i])
+    }
+  }
+  return sell[k]
+}