s0016

include/s0016_3sum_closest.hpp

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+#ifndef S0016_3SUM_CLOSEST
+#define S0016_3SUM_CLOSEST
+
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+class Solution {
+ public:
+  int threeSumClosest(vector<int>& nums, int target);
+};
+
+#endif

src/s0016_3sum_closest.cpp

@@ -0,0 +1,27 @@
+#include "s0016_3sum_closest.hpp"
+
+// 和上一道一样，排序 + 双指针
+
+int Solution::threeSumClosest(vector<int>& nums, int target) {
+  int sum = nums[0] + nums[1] + nums[2];
+  int len = nums.size();
+  sort(nums.begin(), nums.end());
+  for (int i{1}; i < len - 1; i++) {
+    for (int j{0}, k = len - 1; j != k && i != j && i != k;) {
+      if (nums[i] + nums[j] + nums[k] > target) {
+        if (abs(nums[i] + nums[j] + nums[k] - target) < abs(sum - target)) {
+          sum = nums[i] + nums[j] + nums[k];
+        }
+        k--;
+      } else if (nums[i] + nums[j] + nums[k] < target) {
+        if (abs(nums[i] + nums[j] + nums[k] - target) < abs(sum - target)) {
+          sum = nums[i] + nums[j] + nums[k];
+        }
+        j++;
+      } else {
+        return nums[i] + nums[j] + nums[k];
+      }
+    }
+  }
+  return sum;
+}

tests/s0016_3sum_closest.cpp

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+#include "s0016_3sum_closest.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Problem16, Case1) {
+  vector<int> nums{-1, 2, 1, -4};
+  int target{1};
+  int o{2};
+  Solution solution;
+  EXPECT_EQ(solution.threeSumClosest(nums, target), o);
+}
+
+TEST(Problem16, Case2) {
+  vector<int> nums{0, 0, 0};
+  int target{1};
+  int o{0};
+  Solution solution;
+  EXPECT_EQ(solution.threeSumClosest(nums, target), o);
+}