add: 220609-CN [cpp]

cpp/2206/220609-CN.cpp

@@ -0,0 +1,77 @@
+#include <vector>
+#include <random>
+#include <ctime>
+#include <algorithm>
+
+/**
+ * 497. Random Point in Non-overlapping Rectangles
+ *
+ * You are given an array of non-overlapping axis-aligned rectangles rects where rects[i] = [ai, bi, xi, yi] indicates that (ai, bi) is the bottom-left corner point of the ith rectangle and (xi, yi) is the top-right corner point of the ith rectangle. Design an algorithm to pick a random integer point inside the space covered by one of the given rectangles. A point on the perimeter of a rectangle is included in the space covered by the rectangle.
+ * Any integer point inside the space covered by one of the given rectangles should be equally likely to be returned.
+ * Note that an integer point is a point that has integer coordinates.
+ * Implement the Solution class:
+ * Solution(int[][] rects) Initializes the object with the given rectangles rects.
+ * int[] pick() Returns a random integer point [u, v] inside the space covered by one of the given rectangles.
+ */
+
+class Solution {
+private:
+	std::vector<std::vector<int>> r;
+
+	std::vector<int> pSum;
+
+	int total;
+
+	std::mt19937 rnd;
+
+	int randIntN(int n) {
+		return rnd() % n;
+	}
+
+public:
+	explicit Solution(std::vector<std::vector<int>> rects) {
+		r = std::move(rects);
+		rnd = std::mt19937(std::time(nullptr));
+		pSum = std::vector<int>(r.size());
+		for (int i = 1; i < r.size(); ++i) {
+			const auto& x = r[i - 1];
+			pSum[i] = pSum[i - 1] + (x[2] - x[0] + 1) * (x[3] - x[1] + 1);
+		}
+		total = pSum.back() + (r.back()[2] - r.back()[0] + 1) * (r.back()[3] - r.back()[1] + 1);
+	}
+
+	std::vector<int> pick() {
+		int pno = randIntN(total);
+		int rno = std::upper_bound(pSum.begin(), pSum.end(), pno) - pSum.begin() - 1;
+		const auto& t = r[rno];
+		int x1 = t[0],
+			y1 = t[1],
+			x2 = t[2],
+			y2 = t[3],
+			rn = pno - pSum[rno];
+		return {x1 + rn / (y2 - y1 + 1), y1 + rn % (y2 - y1 + 1)};
+	}
+};
+
+int main() {
+	std::vector<std::vector<int>> rect {{82918473,-57180867,82918476,-57180863},{83793579,18088559,83793580,18088560},{66574245,26243152,66574246,26243153},{72983930,11921716,72983934,11921720}};
+	Solution s(rect);
+
+	for (int i = 0; ; ++i) {
+		auto x = s.pick();
+		bool OK = false;
+		for (const auto& r : rect) {
+			if (x[0] >= r[0] && x[0] <= r[2] && x[1] >= r[1] && x[1] <= r[3]) {
+				OK = true;
+				break;
+			}
+		}
+		if (!OK) {
+			std::printf("0x%08X: Failed when returning {%d, %d}\n", i, x[0], x[1]);
+		} else {
+		//	std::printf("0x%08X: OK\n", i);
+		}
+	}
+
+	return 0;
+}