Commit 484e08a

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Merge pull request #22 from mihirs16/master

added leetcode questions

2 parents c7c4498 + 40c285c commit 484e08aCopy full SHA for 484e08a

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	`1`	`+# construct quad tree \| leetcode 427 \| https://leetcode.com/problems/construct-quad-tree/`
	`2`	`+# recursively call each quad of the grid and check if each quad is uniform or not`
	`3`	`+`
	`4`	`+# Definition for a QuadTree node.`
	`5`	`+class Node:`
	`6`	`+ def __init__(self, val, isLeaf, topLeft, topRight, bottomLeft, bottomRight):`
	`7`	`+ self.val = val`
	`8`	`+ self.isLeaf = isLeaf`
	`9`	`+ self.topLeft = topLeft`
	`10`	`+ self.topRight = topRight`
	`11`	`+ self.bottomLeft = bottomLeft`
	`12`	`+ self.bottomRight = bottomRight`
	`13`	`+`
	`14`	`+`
	`15`	`+class Solution:`
	`16`	`+ def construct(self, grid: list[list[int]]) -> Node:`
	`17`	`+ def checkThisQuad(row, col, n) -> bool:`
	`18`	`+ for i in range(row, row + n):`
	`19`	`+ for j in range(col, col + n):`
	`20`	`+ if grid[i][j] != grid[row][col]:`
	`21`	`+ return False`
	`22`	`+ return True`
	`23`	`+`
	`24`	`+ def quadTree(row, col, n):`
	`25`	`+ if checkThisQuad(row, col, n):`
	`26`	`+ return Node(grid[row][col], 1, None, None, None, None)`
	`27`	`+`
	`28`	`+`
	`29`	`+ return Node(grid[row][col], 0,`
	`30`	`+ quadTree(row, col, n//2),`
	`31`	`+ quadTree(row, col + n//2, n//2),`
	`32`	`+ quadTree(row + n//2, col, n//2),`
	`33`	`+ quadTree(row + n//2, col + n//2, n//2)`
	`34`	`+ )`
	`35`	`+`
	`36`	`+ return quadTree(0, 0, len(grid))`
	`37`	`+`

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	`1`	`+# target sum \| leetcode 494 \| https://leetcode.com/problems/target-sum/`
	`2`	`+# 0/1 knapsack to decide +/- and cache (index, total)`
	`3`	`+`
	`4`	`+class Solution:`
	`5`	`+ def findTargetSumWays(self, nums: list[int], target: int) -> int:`
	`6`	`+ N = len(nums)`
	`7`	`+ mem = dict()`
	`8`	`+`
	`9`	`+ if N == 0:`
	`10`	`+ return 0`
	`11`	`+`
	`12`	`+ def knapsack(n, s):`
	`13`	`+ if n == N:`
	`14`	`+ return 1 if s == target else 0`
	`15`	`+`
	`16`	`+ if (n, s) in mem:`
	`17`	`+ return mem[(n, s)]`
	`18`	`+`
	`19`	`+ mem[(n, s)] = knapsack(n+1, s + nums[n]) + knapsack(n+1, s - nums[n])`
	`20`	`+ return mem[(n, s)]`
	`21`	`+`
	`22`	`+ return knapsack(0, 0)`

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