20210104

20210104/main.go

@@ -1,9 +1,40 @@
 package main
 
+import "strings"
+
 func main() {
 
 }
 
 func solution(s string) string {
-	return ""
+	var stack [26]int
+	max := 0
+	for i := 0; i < len(s); i++ {
+		index := s[i] - 'a'
+		stack[index]++
+		if stack[index] > max {
+			max = stack[index]
+		}
+	}
+	sb := strings.Builder{}
+	up := true
+	for i := 0; i < max; i++ {
+		if up {
+			for j := 0; j < len(stack); j++ {
+				if stack[j] > 0 {
+					sb.WriteByte(uint8(j) + 'a')
+					stack[j]--
+				}
+			}
+		} else {
+			for j := len(stack) - 1; j >= 0; j-- {
+				if stack[j] > 0 {
+					sb.WriteByte(uint8(j) + 'a')
+					stack[j]--
+				}
+			}
+		}
+		up = !up
+	}
+	return sb.String()
 }

20210104/main_test.go

@@ -18,6 +18,34 @@ func Test_solution(t *testing.T) {
 			},
 			"abccbaabccba",
 		},
+		{
+			"test2",
+			args{
+				"rat",
+			},
+			"art",
+		},
+		{
+			"test3",
+			args{
+				"leetcode",
+			},
+			"cdelotee",
+		},
+		{
+			"test4",
+			args{
+				"ggggggg",
+			},
+			"ggggggg",
+		},
+		{
+			"test5",
+			args{
+				"spo",
+			},
+			"ops",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {