create 2002 in go

go/2002-maximum-product-of-the-length-of-two-palindromic-subsequences.go

@@ -0,0 +1,46 @@
+func maxProduct(s string) (res int) {
+ dp := make([]int, 1<<len(s))
+ mask := (1 << len(s)) - 1
+ palindromeSize := func(s string, mask int) (res int) {
+ i, j := 0, len(s)
+ for i <= j {
+ if mask&(1<<i) == 0 {
+ i++
+ } else if mask&(1<<j) == 0 {
+ j--
+ } else if s[i] != s[j] {
+ return 0
+ } else {
+ if i == j {
+ res++
+ } else {
+ res += 2
+ }
+ i++
+ j--
+ }
+ }
+ return res
+ }
+
+ max := func(a, b int) int {
+ if a > b {
+ return a
+ }
+ return b
+ }
+
+ for m := 1; m <= mask; m++ {
+ dp[m] = palindromeSize(s, m)
+ }
+
+ for m1 := mask; m1 > 0; m1-- {
+ if dp[m1]*(len(s)-dp[m1]) <= res {
+ continue
+ }
+ for m2 := mask ^ m1; m2 > 0; m2 = (m2 - 1) & (mask ^ m1) {
+ res = max(res, dp[m1]*dp[m2])
+ }
+ }
+ return
+}