solve problem Pascals Triangle

Author: P-ppc

README.md

@@ -56,6 +56,7 @@ All solutions will be accepted!
 |82|[Remove Duplicates From Sorted List II](https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list-ii/description/)|[java/py/js](./algorithms/RemoveDuplicatesFromSortedListII)|Medium|
 |811|[Subdomain Visit Count](https://leetcode-cn.com/problems/subdomain-visit-count/description/)|[java/py/js](./algorithms/SubdomainVisitCount)|Easy|
 |637|[Average Of Levels In Binary Tree](https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/description/)|[java/py/js](./algorithms/AverageOfLevelsInBinaryTree)|Easy|
+|118|[Pascals Triangle](https://leetcode-cn.com/problems/pascals-triangle/description/)|[java/py/js](./algorithms/PascalsTriangle)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/PascalsTriangle/README.md

@@ -0,0 +1,2 @@
+# Pascals Triangle
+This problem is easy to solve

algorithms/PascalsTriangle/Solution.java

@@ -0,0 +1,21 @@
+class Solution {
+    public List<List<Integer>> generate(int numRows) {
+        List<List<Integer>> res = new ArrayList<List<Integer>>();
+        for (int i = 0; i < numRows; i++) {
+            List<Integer> row = new ArrayList<Integer>();
+            row.add(1);
+            if (i > 0) {
+                List<Integer> lastRow = res.get(res.size() - 1);
+                for (int j = 0; j < lastRow.size(); j++) {
+                    if (j + 1 < lastRow.size()) {
+                        row.add(lastRow.get(j) + lastRow.get(j + 1));
+                    } else {
+                        row.add(lastRow.get(j));
+                    }
+                }
+            }
+            res.add(row);
+        }
+        return res;
+    }
+}

algorithms/PascalsTriangle/solution.js

@@ -0,0 +1,24 @@
+/**
+ * @param {number} numRows
+ * @return {number[][]}
+ */
+var generate = function(numRows) {
+    let res = []
+    for (let i = 0; i < numRows; i++) {
+        if (i == 0) {
+            res.push([1])
+        } else {
+            temp = [1]
+            last = res[res.length - 1]
+            for (let j = 0; j < last.length; j++) {
+                if (j + 1 < last.length) {
+                    temp.push(last[j] + last[j + 1])
+                } else {
+                    temp.push(last[j])
+                }
+            }
+            res.push(temp)
+        }
+    }    
+    return res
+};

algorithms/PascalsTriangle/solution.py

@@ -0,0 +1,20 @@
+class Solution(object):
+    def generate(self, numRows):
+        """
+        :type numRows: int
+        :rtype: List[List[int]]
+        """
+        res = []
+        for i in range(0, numRows): 
+            if len(res) == 0:
+                res.append([1])
+                continue
+            last = res[-1]
+            temp = [1]
+            for j in range(0, len(last)):
+                if j + 1 < len(last):
+                    temp.append(last[j] + last[j + 1])
+                else:
+                    temp.append(last[j])
+            res.append(temp)
+        return res