101 lines
2.3 KiB
Rust
101 lines
2.3 KiB
Rust
/**
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* [40] Combination Sum II
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*/
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pub struct Solution {}
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// submission codes start here
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use std::collections::HashMap;
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use std::iter::FromIterator;
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impl Solution {
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pub fn combination_sum2(candidates: Vec<i32>, target: i32) -> Vec<Vec<i32>> {
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let mut frequency_map = HashMap::new();
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for c in candidates {
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let entry = frequency_map.entry(c).or_insert(0);
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*entry += 1;
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}
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// (number, count)
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let mut candidates = Vec::from_iter(frequency_map.into_iter());
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candidates.sort();
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let mut path = vec![];
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let mut result = vec![];
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Self::dfs(&candidates, 0, target, &mut path, &mut result);
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result
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}
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fn dfs(
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candidates: &Vec<(i32, i32)>,
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pos: usize,
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rest: i32,
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path: &mut Vec<i32>,
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result: &mut Vec<Vec<i32>>,
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) {
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if rest == 0 {
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result.push(path.clone());
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return;
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}
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if pos >= candidates.len() || rest < candidates[pos].0 {
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return;
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}
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// 不选择pos
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Self::dfs(candidates, pos + 1, rest, path, result);
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// 选择pos
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// 能够选择pos最多的次数
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let count = candidates[pos].1.min(rest / candidates[pos].0);
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for i in 1..=count {
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path.push(candidates[pos].0);
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Self::dfs(
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candidates,
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pos + 1,
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rest - candidates[pos].0 * i,
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path,
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result,
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);
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}
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// dfs结束弹出
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for _ in 1..=count {
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path.pop();
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}
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::collections::HashSet;
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fn vec_equal_helper(expect: Vec<Vec<i32>>, actual: Vec<Vec<i32>>) {
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let set: HashSet<Vec<i32>> = HashSet::from_iter(expect.into_iter());
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assert_eq!(set.len(), actual.len());
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for array in actual {
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assert!(set.contains(&array));
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}
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}
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#[test]
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fn test_40() {
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vec_equal_helper(
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vec![vec![1, 1, 6], vec![1, 2, 5], vec![1, 7], vec![2, 6]],
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Solution::combination_sum2(vec![10, 1, 2, 7, 6, 1, 5], 8),
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);
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vec_equal_helper(
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vec![vec![1, 2, 2], vec![5]],
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Solution::combination_sum2(vec![2, 5, 2, 1, 2], 5),
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);
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}
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}
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