add

Author: kamyu104

C++/valid-triangle-number.cpp

@@ -0,0 +1,24 @@
+// Time:  O(n^2)
+// Space: O(1)
+
+class Solution {
+public:
+    int triangleNumber(vector<int>& nums) {
+        int result = 0;
+        sort(nums.begin(), nums.end());
+        for (int i = 0; i + 2 < nums.size(); ++i) {
+            if (nums[i] == 0) {
+                continue;
+            }
+            auto k = i + 2;
+            for (int j = i + 1; j + 1 < nums.size(); ++j) {
+                while (k < nums.size() && nums[i] + nums[j] > nums[k]) {
+                    ++k;
+                }
+                result += k - j - 1;
+            }
+        }
+        return result;
+    }
+};
+