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@@ -0,0 +1,26 @@
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+func maximumSwap(num int) int {
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+ digit := make([]int, 0)
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+ for i := num; 0 < i; i /= 10 {
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+ digit = append(digit, i%10)
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+ }
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+ n := len(digit)
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+ max := make([]int, n)
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+ for i := 1; i < n; i++ {
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+ max[i] = i // max[i]: the maximum digit that lower than the ith digit
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+ if digit[i] <= digit[max[i-1]] {
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+ max[i] = max[i-1]
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+ }
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+ }
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+ for i := n - 1; 0 <= i; i-- {
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+ if digit[i] < digit[max[i]] {
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+ digit[i], digit[max[i]] = digit[max[i]], digit[i]
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+ res := 0
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+ for j := n - 1; 0 <= j; j-- {
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+ res *= 10
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+ res += digit[j]
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+ }
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+ return res
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+ }
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+ }
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+ return num
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+}
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