feat: 三数之和

Author: sl1673495

三数之和.js

@@ -0,0 +1,41 @@
+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+var twoSum = function(nums, target) {
+  let map = new Map()
+  var results = []
+  for (let i = 0; i < nums.length; i++) {
+    let num = nums[i]
+    let result = map.get(target - num)
+    if (result !== undefined) {
+      results.push([nums[result], num])
+    }
+    map.set(num, i)
+  }
+  return results
+}
+
+var threeSum = function(nums) {
+  nums.sort((a, b) => a - b)
+  var set = new Set()
+  var results = []
+  for (var i = 0; i < nums.length - 2; i++) {
+    let find = twoSum(nums.slice(i + 1), -nums[i])
+    if (find) {
+      find.forEach((arr) => {
+        if (!set.has(arr.join(''))) {
+          results.push([nums[i], ...arr])
+        }
+        set.add(arr.join(''))
+      })
+    }
+  }
+  return results
+}
+
+console.log(threeSum([-1,0,1,2,-1,-4]))
+
+/**
+ * 利用两数之和的变形来求解，循环判断第三个数的负数是否能和另外两个数相加得到。
+ */