59 lines
2.0 KiB
Rust
59 lines
2.0 KiB
Rust
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// 中位数贪心，枚举结果中的中间那个1的位置。
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// 预处理一下前缀和和后缀和，这样在枚举的过程中就可以用二分查找，实现O(n\log n)复杂度。
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// nums = [1 0 0 1 0 1]
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// pa = [1 1 1 2 2 3]
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// pasum= [0 0 0 3 3 8]
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struct Solution;
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#[inline]
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fn sum(start: i32, length: i32) -> i64 {
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(2 * start as i64 + length as i64 - 1) * length as i64 >> 1
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}
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impl Solution {
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pub fn min_moves(nums: Vec<i32>, k: i32) -> i32 {
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if k == 1 {
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return 0;
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}
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let n = nums.len();
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let mut pa = vec![0;n+1];
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let mut pa_sum = vec![0;n+1];
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for i in 1..=n {
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pa[i] = pa[i-1] + nums[i-1];
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if nums[i-1] == 1 {
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pa_sum[i] = pa_sum[i-1] + i as i64 - 1;
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} else {
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pa_sum[i] = pa_sum[i-1];
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}
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}
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let part = k >> 1;
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let mut res = i64::MAX;
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for (i,&x) in nums.iter().enumerate() {
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let i = i as i32;
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if x == 0 { continue; }
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let lsr = if k & 1 == 0 {i} else {i-1};
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let rsl = i + 1;
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if lsr < 0 || rsl >= n as i32 {continue;}
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if let Ok(li) = pa[0..=lsr as usize+1].binary_search_by_key(&-part, |t|t-pa[lsr as usize+1]) {
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if let Ok(ri) = pa[rsl as usize+1..=n].binary_search_by_key(&part, |t|t-pa[rsl as usize]) {
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let right_sum = pa_sum[ri+rsl as usize + 1] - pa_sum[rsl as usize] - sum(rsl, part);
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let left_sum = sum(lsr - part + 1, part) - pa_sum[lsr as usize + 1] + pa_sum[li];
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res = res.min(left_sum + right_sum);
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}
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}
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}
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res as i32
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}
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}
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fn main() {
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let mut buf = String::new();
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std::io::stdin().read_line(&mut buf).ok();
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let nums: Vec<i32> = buf.trim().split(' ').map(|x|x.parse::<i32>().unwrap()).collect::<Vec<i32>>();
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buf.clear();
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std::io::stdin().read_line(&mut buf).ok();
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let k: i32 = buf.trim().parse::<i32>().unwrap();
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println!("{}", Solution::min_moves(nums, k));
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}
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