121 finish

Author: aQua

Algorithms/0121.best-time-to-buy-and-sell-stock/best-time-to-buy-and-sell-stock.go

@@ -2,11 +2,14 @@ package Problem0121
 
 func maxProfit(prices []int) int {
 	max := 0
-	for i, v := range prices {
-		for j := i + 1; j < len(prices); j++ {
-			if max < prices[j]-v {
-				max = prices[j] - v
-			}
+	temp := 0
+	for i := 1; i < len(prices); i++ {
+		temp += prices[i] - prices[i-1]
+		if temp < 0 {
+			temp = 0
+		}
+		if max < temp {
+			max = temp
 		}
 	}
 

Algorithms/0121.best-time-to-buy-and-sell-stock/best-time-to-buy-and-sell-stock_test.go

@@ -27,6 +27,15 @@ func Test_Problem0121(t *testing.T) {
 
 	qs := []question{
 
+		question{
+			para{
+				[]int{7, 2, 1, 5, 3, 6, 4},
+			},
+			ans{
+				5,
+			},
+		},
+
 		question{
 			para{
 				[]int{7, 1, 5, 3, 6, 4},