63 lines
1.5 KiB
Rust
63 lines
1.5 KiB
Rust
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struct Solution;
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struct Sol;
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impl Sol {
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fn solve(mut x: i64, limit: i64, mut s: i64) -> i64 {
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let mut pow = vec![1i64;17];
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for i in 1..17 {
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pow[i] = pow[i-1] * 10;
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}
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let mut cnt = vec![0;17];
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let m = s;
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let mut s_len = 0;
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while s != 0 {
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s_len += 1;
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s /= 10;
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}
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let pass = m <= x % pow[s_len];
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let mut x_len = 0;
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let mut x_digit = vec![];
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x_digit.push(0);
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while x != 0 {
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x_len += 1;
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x_digit.push(x % 10);
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x /= 10;
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}
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if s_len > x_len {
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return 0;
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}
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for i in 1..=x_len {
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if i <= s_len {
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cnt[i] = 1;
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} else {
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cnt[i] = cnt[i-1] * (limit + 1);
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}
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}
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let mut res = 0;
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let mut f = true;
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for i in (s_len+1..=x_len).rev() {
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res += cnt[i-1] * (limit.min(x_digit[i] - 1) + 1);
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if limit < x_digit[i] {
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f = false;
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break;
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}
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}
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if f && pass {
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res += 1;
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}
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res
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}
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}
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impl Solution {
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pub fn number_of_powerful_int(start: i64, finish: i64, limit: i32, s: String) -> i64 {
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let upper = Sol::solve(finish , limit as i64, s.parse().unwrap());
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let lower = Sol::solve(start - 1, limit as i64, s.parse().unwrap());
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upper - lower
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}
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}
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fn main() {
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println!("{}", Solution::number_of_powerful_int(1, 1000000000000000, 4, "1".to_string()));
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}
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