update

hard/420.strong-password-checker.go

@@ -35,20 +35,27 @@ func strongPasswordChecker(s string) int {
 	if n < 6 {
 		return miss + maxInt(0, 6-n-miss) // Repeat && missing can be both solved by insert
 	}
-	exceed, m := maxInt(0, n-20), len(repeat)
-	for k := 2; 1 <= k; k-- {
+	exceed, replace, m := maxInt(0, n-20), 0, len(repeat)
+	res := exceed
+	for k := 1; k <= 2; k++ { // Smaller k first, cauz aaa -> aa: 1 step, aaaa -> xaa: 2 step
 		for i := 0; i < m && 0 < exceed; i++ {
 			if repeat[i] < 3 || repeat[i]%3 != k-1 {
 				continue
 			}
-			repeat[i] -= minInt(exceed, k)
-			exceed -= k
+			dec := minInt(exceed, k)
+			repeat[i], exceed = repeat[i]-dec, exceed-dec
 		}
 	}
 	for i := 0; i < m; i++ {
-		
+		if 3 <= repeat[i] && 0 < exceed {
+			dec := minInt(exceed, repeat[i]-2) // 3k+2 -> 2 to make exceed == 0
+			repeat[i], exceed = repeat[i]-dec, exceed-dec
+		}
+		if 3 <= repeat[i] {
+			replace += repeat[i] / 3
+		}
 	}
-	return 0
+	return res + maxInt(miss, replace)
 }
 
 func minInt(x, y int) int {
@@ -64,4 +71,3 @@ func maxInt(x, y int) int {
 	}
 	return x
 }
-