↓Skip to main content
  1. Posts/

LeetCode-LCP74 最强祝福力场

·1 min·
Table of Contents

LeetCode-LCP74 最强祝福力场 #

Solution 1 #

离散化 + 二维差分数组.

代码如下:

class Solution:
    def fieldOfGreatestBlessing(self, forceField: List[List[int]]) -> int:
        x_set, y_set = set(), set()
        for (x, y, side) in forceField:
            x_set.add(2 * x - side)
            x_set.add(2 * x + side)
            y_set.add(2 * y - side)
            y_set.add(2 * y + side)
            
        xs, ys = sorted(x_set), sorted(y_set)

        m, n = len(xs), len(ys)
        d = [[0 for _ in range(n + 1)] for _ in range(m + 1)]
        for (x, y, side) in forceField:
            i1 = bisect_left(xs, 2 * x - side)
            j1 = bisect_left(ys, 2 * y - side)
            i2 = bisect_left(xs, 2 * x + side)
            j2 = bisect_left(ys, 2 * y + side)
            d[i1][j1] += 1
            d[i1][j2 + 1] -= 1
            d[i2 + 1][j1] -= 1
            d[i2 + 1][j2 + 1] += 1
        
        ans = 0
        for i in range(m):
            for j in range(n):
                d[i][j] += (d[i - 1][j] if i > 0 else 0) + (d[i][j - 1] if j > 0 else 0) - (d[i - 1][j - 1] if i > 0 and j > 0 else 0)
                ans = max(ans, d[i][j])
        return ans