solve 40

Author: Zhang Xiaodong

src/solution/mod.rs

@@ -35,3 +35,4 @@ mod s0036_valid_sudoku;
 mod s0037_sudoku_solver;
 mod s0038_count_and_say;
 mod s0039_combination_sum;
+mod s0040_combination_sum_ii;

src/solution/s0040_combination_sum_ii.rs

@@ -0,0 +1,109 @@
+/**
+ * [40] 组合总和 II
+ *
+ * 给定一个候选人编号的集合 candidates 和一个目标数 target ，找出 candidates 中所有可以使数字和为 target 的组合。
+ * candidates 中的每个数字在每个组合中只能使用 一次 。
+ * 注意：解集不能包含重复的组合。
+ *  
+ * 示例 1:
+ *
+ * 输入: candidates = [10,1,2,7,6,1,5], target = 8,
+ * 输出:
+ * [
+ * [1,1,6],
+ * [1,2,5],
+ * [1,7],
+ * [2,6]
+ * ]
+ * 示例 2:
+ *
+ * 输入: candidates = [2,5,2,1,2], target = 5,
+ * 输出:
+ * [
+ * [1,2,2],
+ * [5]
+ * ]
+ *  
+ * 提示:
+ *
+ * 	1 <= candidates.length <= 100
+ * 	1 <= candidates[i] <= 50
+ * 	1 <= target <= 30
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.cn/problems/combination-sum-ii/
+// discuss: https://leetcode.cn/problems/combination-sum-ii/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn combination_sum2(candidates: Vec<i32>, target: i32) -> Vec<Vec<i32>> {
+        let mut candidates = candidates.clone();
+        candidates.sort();
+
+        let mut res = vec![];
+
+        let mut sum = candidates[0];
+        let mut curr = vec![candidates[0]];
+        let mut curr_idx = vec![0];
+        let mut last_idx = 0;
+
+        'outer: while curr.len() > 0 {
+            // println!("{:?}", curr);
+            if sum == target {
+                res.push(curr.clone());
+            }
+            if sum < target {
+                let i = last_idx + 1;
+                if i < candidates.len() {
+                    last_idx = i;
+                    curr_idx.push(i);
+                    curr.push(candidates[i]);
+                    sum += candidates[i];
+                    continue;
+                }
+            }
+            'poping: while let Some(v) = curr.pop() {
+                last_idx = curr_idx.pop().unwrap();
+                sum -= v;
+
+                let mut nexti = last_idx;
+
+                while candidates[nexti] == v {
+                    // println!("nexti: {}", nexti);
+                    nexti += 1;
+                    if nexti == candidates.len() {
+                        continue 'poping;
+                    }
+                }
+                last_idx = nexti;
+                curr_idx.push(last_idx);
+                curr.push(candidates[last_idx]);
+                sum += candidates[last_idx];
+                continue 'outer;
+            }
+        }
+        res
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_40() {
+        assert_eq!(
+            Solution::combination_sum2(vec![2, 5, 2, 1, 2], 5),
+            vec![vec![1, 2, 2], vec![5]],
+        );
+        assert_eq!(
+            Solution::combination_sum2(vec![10, 1, 2, 7, 6, 1, 5], 8),
+            vec![vec![1, 1, 6], vec![1, 2, 5], vec![1, 7], vec![2, 6]],
+        )
+    }
+}