50 lines
912 B
Go
50 lines
912 B
Go
package q909
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func coord(n, num int) (x, y int) {
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num -= 1
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row := num / n
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y = n - row - 1
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x = num % n
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if row%2 == 1 {
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x = n - 1 - x
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}
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return
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}
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func snakesAndLadders(board [][]int) int {
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n, sqN := len(board), len(board)*len(board)
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leastRolls := make([]int, sqN)
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if len(leastRolls) == 1 {
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return 0
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}
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queue := make([]int, 0, sqN)
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queue = append(queue, 1)
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for ; len(queue) > 0; queue = queue[1:] {
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cur := queue[0]
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for dist := 1; dist <= 6 && cur+dist <= sqN; dist++ {
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next := cur + dist
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x, y := coord(n, next)
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if board[y][x] != -1 {
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next = board[y][x]
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}
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rolls := leastRolls[cur-1] + 1
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if (next > 1 && leastRolls[next-1] == 0) || rolls < leastRolls[next-1] {
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leastRolls[next-1] = rolls
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if next == sqN {
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return rolls
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}
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queue = append(queue, next)
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}
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}
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}
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l := leastRolls[sqN-1]
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if l == 0 {
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return -1
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}
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return 0
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}
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var _ = snakesAndLadders
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