Kotlin: 91. Decode Ways

Jay-0331 · Oct 1, 2022 · cb8e1b1 · cb8e1b1
1 parent 18ee23d
commit cb8e1b1
Showing 1 changed file with 22 additions and 0 deletions.
diff --git a/kotlin/91-Decode-Ways.kt b/kotlin/91-Decode-Ways.kt
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+class Solution {
+ fun numDecodings(s: String): Int {
+ val n = s.length
+ val dp = IntArray(n+1)
+ dp[0] = 1
+ dp[1] = if (s[0] == '0') 0 else 1
+
+ for (i in 2..n) {
+ val curr = s[i-1] - '0'
+ val prev = s[i-2] - '0'
+ val num = 10*prev + curr
+
+ if (curr > 0)
+ dp[i] += dp[i-1]
+
+ if (num >= 10 && num <= 26)
+ dp[i] += dp[i-2]
+ }
+
+ return dp[n]
+ }
+}