Codeforces Round #627 (Div. 3) D. Pair of Topics（二分，思惟）

传送门html 题意： The pair of topics 𝑖 and 𝑗 (𝑖<𝑗) is called good if 𝑎𝑖+𝑎𝑗>𝑏𝑖+𝑏𝑗 (i.e. it is more interesting for the teacher). 找知足这个不等式的对数ios 思路： (单独写的a[i]都是表明题意中的a[i]-b[i]) 移项得 𝑎𝑖-𝑏𝑖>𝑏𝑗-

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