67 lines
1.3 KiB
Go
67 lines
1.3 KiB
Go
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package main
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import (
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"unicode"
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)
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func diffWaysToCompute(expression string) []int {
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n := len(expression)
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dp := make([][][]int, n)
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for i := range dp {
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dp[i] = make([][]int, n)
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}
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computeBase := func() {
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for i, c := range expression {
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if !unicode.IsDigit(c) {
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continue
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}
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digit := int(c - '0')
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dp[i][i] = append(dp[i][i], digit)
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if i+1 < n && unicode.IsDigit(rune(expression[i+1])) {
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nextDigit := int(expression[i+1] - '0')
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dp[i][i+1] = append(dp[i][i+1], digit*10+nextDigit)
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}
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}
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}
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computeBase()
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precompute := func(op byte, left, right, results []int) []int {
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for _, l := range left {
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for _, r := range right {
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switch op {
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case '+':
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results = append(results, l+r)
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case '-':
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results = append(results, l-r)
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case '*':
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results = append(results, l*r)
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}
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}
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}
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return results
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}
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computeSubexpression := func(l, r int) {
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for mid := l; mid <= r; mid++ {
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if unicode.IsDigit(rune(expression[mid])) {
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continue
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}
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left, right := dp[l][mid-1], dp[mid+1][r]
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dp[l][r] = precompute(expression[mid], left, right, dp[l][r])
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}
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}
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for length := 3; length <= n; length++ {
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for l := 0; l+length-1 < n; l++ {
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r := l + length - 1
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computeSubexpression(l, r)
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}
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}
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return dp[0][n-1]
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}
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