package main

import "fmt"

func main() {
    n := 15
    ret := findIntegers(n)
    fmt.Println(ret)
}

func findIntegers(n int) int {
    i := 31
    for ; i >= 0; i-- {
        if (n & (1 << i)) != 0 {
            break
        }
    }
    // for循环出来之后，i表示，n最高位的1，在哪？
    // 从这个位置，往右边低位上走！
    dp := make([][][]int, 2)
    for ii := 0; ii < 2; ii++ {
        dp[ii] = make([][]int, 2)
        for j := 0; j < 2; j++ {
            dp[ii][j] = make([]int, i+2)
        }
    }
    return f(0, 0, i, n, dp)
}

func f(pre, alreadyLess, index, num int, dp [][][]int) int {
    if index == -1 {
        return 1
    }
    if dp[pre][alreadyLess][index] != 0 {
        return dp[pre][alreadyLess][index]
    }
    ans := 0
    if pre == 1 {
        ans = f(0, getMax(alreadyLess, twoSelectOne((num&(1<<index)) != 0, 1, 0)), index-1, num, dp)
    } else {
        if (num&(1<<index)) == 0 && alreadyLess == 0 {
            ans = f(0, alreadyLess, index-1, num, dp)
        } else {
            ans = f(1, alreadyLess, index-1, num, dp) + f(0, getMax(alreadyLess, twoSelectOne((num&(1<<index)) != 0, 1, 0)), index-1, num, dp)
        }
    }
    dp[pre][alreadyLess][index] = ans
    return ans
}

func getMax(a, b int) int {
    if a > b {
        return a
    } else {
        return b
    }
}

func twoSelectOne(c bool, a, b int) int {
    if c {
        return a
    } else {
        return b
    }
}