Create exclusive-time-of-functions.py

Author: kamyu104

Python/exclusive-time-of-functions.py

@@ -0,0 +1,62 @@
+# Time:  O(n)
+# Space: O(n)
+
+# Given the running logs of n functions that are executed 
+# in a nonpreemptive single threaded CPU, find the exclusive time of these functions.
+#
+# Each function has a unique id, start from 0 to n-1.
+# A function may be called recursively or by another function.
+#
+# A log is a string has this format : function_id:start_or_end:timestamp.
+# For example, "0:start:0" means function 0 starts from the very beginning of time 0.
+# "0:end:0" means function 0 ends to the very end of time 0.
+#
+# Exclusive time of a function is defined as the time spent within this function,
+# the time spent by calling other functions should not be considered as
+# this function's exclusive time.
+# You should return the exclusive time of each function sorted by their function id.
+#
+# Example 1:
+# Input:
+# n = 2
+# logs = 
+# ["0:start:0",
+#  "1:start:2",
+#  "1:end:5",
+#  "0:end:6"]
+# Output:[3, 4]
+#
+# Explanation:
+# Function 0 starts at time 0, then it executes 2 units of time and reaches the end of time 1. 
+# Now function 0 calls function 1, function 1 starts at time 2, executes 4 units of time and end at time 5.
+# Function 0 is running again at time 6, and also end at the time 6, thus executes 1 unit of time. 
+# So function 0 totally execute 2 + 1 = 3 units of time, and function 1 totally execute 4 units of time.
+#
+# Note:
+# Input logs will be sorted by timestamp, NOT log id.
+# Your output should be sorted by function id,
+# which means the 0th element of your output corresponds to the exclusive time of function 0.
+# Two functions won't start or end at the same time.
+# Functions could be called recursively, and will always end.
+# 1 <= n <= 100
+
+class Solution(object):
+    def exclusiveTime(self, n, logs):
+        """
+        :type n: int
+        :type logs: List[str]
+        :rtype: List[int]
+        """
+        result = [0] * n
+        stk, prev = [], 0
+        for log in logs:
+            tokens = log.split(":")
+            if tokens[1] == "start":
+                if stk:
+                    result[stk[-1]] += int(tokens[2]) - prev
+                stk.append(int(tokens[0]))
+                prev = int(tokens[2])
+            else:
+                result[stk.pop()] += int(tokens[2]) - prev + 1
+                prev = int(tokens[2]) + 1
+        return result