Added LeetCode 120 Triangle python solution

Author: Vedant-S

leetcode/python/Dynamic Programming/120.triangle.py

@@ -0,0 +1,20 @@
+class Solution:
+    def minimumTotal(self, triangle):
+        """
+        :type triangle: List[List[int]]
+        :rtype: int
+        """
+        size = len(triangle);
+        num = [0]*size;
+        num[0] = triangle[0][0];
+        for i in range(1,size):
+            num[i] = num[i-1] + triangle[i][i];
+            j = i - 1
+            while j > 0:
+                num[j] = min(num[j], num[j-1]) + triangle[i][j];
+                j -= 1;
+            num[0] = num[0] + triangle[i][0];
+        minm = num[0];
+        for i in range(1,size):
+            minm = min(num[i], minm);
+        return minm;