【leetcode】Contains Duplicate & Rectangle Area（easy）-优快云博客

本文介绍了两个基本的算法问题：如何判断数组中是否存在重复元素，以及如何计算两个矩形在二维平面上的总面积。通过使用集合(set)数据结构解决第一个问题，展示了算法的简洁性和效率；对于第二个问题，则采用了直观的几何计算方法，展现了数学在解决实际问题中的应用。文章旨在提供易于理解的解决方案，同时强调了基础知识在计算机科学中的重要性。

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Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

思路：简单题用set

bool containsDuplicate(vector<int>& nums) {
        unordered_set<int> myset;
        for(int i = 0; i < nums.size(); ++i)
        {
            if(myset.find(nums[i]) != myset.end())
                return true;
            myset.insert(nums[i]);
        }
        return false;
    }

Rectangle Area

Find the total area covered by two rectilinear rectangles in a 2D plane.

Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.

Assume that the total area is never beyond the maximum possible value of int.

思路：求总面积。直观解法。简单题。

int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int up = min(D, H);
        int down = max(B, F);
        int left = max(A, E);
        int right = min(C, G);
        int In = (up > down && right > left) ? (up - down) * (right - left) : 0;
        int area1 = (C - A) * (D - B);
        int area2 = (G - E) * (H - F);

        return area1 + area2 - In;
    }