add 611

fishercoder1534 · fishercoder1534 · commit 87c4d29cd926 · 2017-06-11T09:05:33.000-07:00
diff --git a/README.md b/README.md
@@ -21,6 +21,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
 |617|[Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_617.java) | O(n) |O(h) | Easy | Tree, Recursion
+|611|[Valid Triangle Number](https://leetcode.com/problems/valid-triangle-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_611.java) | O(n^2logn) |O(logn) | Medium | Binary Search
 |609|[Find Duplicate File in System](https://leetcode.com/problems/find-duplicate-file-in-system/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_609.java) | O(n*x) (x is the average length of each string) |O(n*x) | Medium | HashMap
 |606|[Construct String from Binary Tree](https://leetcode.com/problems/construct-string-from-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_606.java) | O(n) |O(n) | Easy | Tree, Recursion
 |605|[Can Place Flowers](https://leetcode.com/problems/can-place-flowers/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_605.java) | O(n) |O(1) | Easy | Array
diff --git a/src/main/java/com/fishercoder/solutions/_611.java b/src/main/java/com/fishercoder/solutions/_611.java
@@ -0,0 +1,46 @@
+package com.fishercoder.solutions;
+
+import java.util.Arrays;
+
+/**
+ * 611. Valid Triangle Number
+ *
+ * Given an array consists of non-negative integers, your task is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.
+
+ Example 1:
+ Input: [2,2,3,4]
+ Output: 3
+
+ Explanation:
+ Valid combinations are:
+ 2,3,4 (using the first 2)
+ 2,3,4 (using the second 2)
+ 2,2,3
+
+ Note:
+ The length of the given array won't exceed 1000.
+ The integers in the given array are in the range of [0, 1000].
+ */
+public class _611 {
+    /**Rule: among three sides, we need to find whether the longest of the three is smaller than the sum of the two shorter one.
+     * If so, then these three could form a valid triangle.*/
+
+    public int triangleNumber(int[] nums) {
+        if (nums == null || nums.length == 0) return 0;
+        Arrays.sort(nums);
+        int triplets = 0;
+        for (int i = 2; i < nums.length; i++) {
+            int left = 0, right = i-1;
+            while (left < right) {
+                if (nums[i] < nums[left] + nums[right]) {
+                    triplets += (right - left);
+                    right--;
+                } else {
+                    left++;
+                }
+            }
+        }
+        return triplets;
+    }
+
+}
diff --git a/src/test/java/com/fishercoder/_611Test.java b/src/test/java/com/fishercoder/_611Test.java
@@ -0,0 +1,33 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._611;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by stevesun on 6/11/17.
+ */
+public class _611Test {
+    private static _611 test;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup(){
+        test = new _611();
+    }
+
+    @Test
+    public void test1(){
+        nums = new int[]{2,2,3,4};
+        assertEquals(3, test.triangleNumber(nums));
+    }
+
+    @Test
+    public void test2(){
+        nums = new int[]{85,88,57,88,61,71,24,12,11,37,37,72,43,22,65,79,34,41,37,74,28,25,73,44,11,84,29,33,21,87,87,21,14,47,45,31,40,33,85,99,47,29,13,82,56,33,47,11,80,59,16,16,57,53,37,20,90,84,97,39,50,22,44,54,67,69,46,58,11,29,89,10,89,30,12,55,30,32,23,74,69,19,48,72,42,12,19,88,39,32,98,89,99,19,78,35,45,16,22,73,86,76,39,50,40,85,85,61,71,97,48,39,21,39,35,11,58,94,37,50,13,78,67,23,24,53,98,41,85,90,85,92,31,11,46,88,83,68,87,33,13,43,95,39,33,40,47,95,28,52,91,60,19,76,80,75,51,64,67,33,43,47,15,80,36,78,33,98,18,15,77,100,60,28,51,86,30,67,48,43,62,23,82,26,93,99,19,93,21,22,34,100,46,94,42,58,31,27,81,47,90,53,85,69,41,29,73,26,23,54,59,83,99,19,28,96,15,56,40,32,32,42,85,43,71,36,98,74,38,91,11,79,62,24,34,29,10,31,54,59,97,35,23,92,72,96,52,45,57,39,69,53,89,46,44,66,43,60,62,28,53,72,82,63,92,39,20,56,72,25,36,33,60,92,29,40,21,53,45,53,80,56,42,67,79,11,39,11,77,82,97,91,55,96,73,48,26,11,90,40,28,21,35,99,25,73,39,62,66,50,72,58,26,91,96,88,98,25,99,27,26,26,40,43,80,21,99,25,94,61,32,49,40,67,91,99,17,99,76,34,21,100,14,98,68,83,54,21,52,84,37,87,100,69,43,76,31,31,39,29,90,82,37,26,36,11,37,95,26,43,29,66,70,99,88,44,37,96,83,38,44,50,48,10,98,67,58,66,74,91,24,19,82,94,94,58,89,73,92,80,19,76,60,23,54,78,55,46,20,27,88,23,93,16,60,97,67,78,86,83,73,48,32,39,83,49,58,82,50,99,67,39,79,48,76,82,72,92,32,98,97,82,44,37,11,50,94,51,89,100,46,95,10,99,39,68,81,34,61,78,95,54,85,31,74,38,95,85,88,45,78,35,82,42,19,12,89,24,42,88,57,79,82,13,22,64,66,42,73,44,54,68,70,15,27,44,72,44,49,42,40,26,50,33,24,56,79,68,100,41,42,92,89,27,50,100,35,54,89,98,32,80,15,90,66,53,27,77,82,97,58,95,70,24,79,27,29,54,90,25,76,26,90,79,67,31,85,15,74,22,59,20,71,62,15,48,31,48,91,89,19,51,17,60,13,65,44,89,19,45,72,84,94,98,21,89,24,10,19,14,26,68,100,44,26,21,65,14,79,93,48,29,60,47,84,54,13,89,45,91,29,15,65,52,39,59,13,25,59,91,22,74,77,62,95,28,86,30,24,61,53,12,16,89,79,64,36,66,47,40,13,94,28,51,64,79,38,28,54,99,11,69,22,42,89,36,62,96,32,50,24,45,90,46,13,31,84,39,84,51,34,97,13,49,10,43,42,47,86,33,76,72,39,26,77,70,100,93,64,20,80,76,48,56,32,38,56,67,15,14,14,11,61,44,31,57,39,65,71,16,68,75,47,81,55,16,80,63,10,73,81,20,20,20,34,37,40,43,44,13,89,31,75,54,37,62,76,63,94,65,82,51,69,56,76,45,12,55,25,29,65,49,16,43,48,65,20,39,81,81,61,85,73,51,81,30,18,62,54,85,85,80,59,63,37,58,32,48,84,64,50,47,99,49,62,69,60,100,67,50,16,22,65,97,58,23,70,27,14,91,84,38,91,37,31,53,100,45,29,64,75,94,70,89,78,81,70,18,79,70,83,70,61,15,42,70,77,45,36,59,65,71,41,82,89,64,48,67,89,28,20,10,99,23,27,65,77,32,96,98,59,64,99,21,77,65,43,37,62,64,78,91,57,98,75,62,92,61,27,40,51,66,55,60,44,83,71,38,34,32,72,22,45,89,26,96,87,59,92,14,94,80,44,36,94,36,21,18,95,80,88,95,87,86,53,14,55,10,24,13,11,10,61,47,76,94,75,85,25,22,22,76,40,43,69,87,30,66,43,74,70,30,94,32,47,88,95,67,25,59,64,12,20,44,48,84,21,34,63,79,21,13,33,71,16,45,37,34,39,24,64,67,42,64,65,55,89,96,72,58,54,17,43,30,54,27,82,66,17,43,41,38,84,37,93,70,75,53,81,35,87,70,77,52,92,90,19,45,33,58,20,77,88,37,49,82,22,24,63,47};
+        assertEquals(105489315, test.triangleNumber(nums));
+    }
+
+}
