s0039

src/s0039_combination_sum.cpp

@@ -0,0 +1,30 @@
+#include "s0039_combination_sum.hpp"
+
+#include <vector>
+
+void dfs(vector<int>& candidates, int target, vector<vector<int>>& ans,
+         vector<int>& combine, int idx) {
+  if (idx == candidates.size()) {
+    return;
+  }
+  if (target == 0) {
+    ans.emplace_back(combine);
+    return;
+  }
+  // 直接跳过
+  dfs(candidates, target, ans, combine, idx + 1);
+  // 选择当前数
+  if (target - candidates[idx] >= 0) {
+    combine.emplace_back(candidates[idx]);
+    dfs(candidates, target - candidates[idx], ans, combine, idx);
+    combine.pop_back();
+  }
+}
+
+vector<vector<int>> Solution::combinationSum(vector<int>& candidates,
+                                             int target) {
+  vector<vector<int>> ans;
+  vector<int> combine;
+  dfs(candidates, target, ans, combine, 0);
+  return ans;
+}