51 lines
1.0 KiB
JavaScript
51 lines
1.0 KiB
JavaScript
/*
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* @lc app=leetcode id=268 lang=javascript
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*
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* [268] Missing Number
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*
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* https://leetcode.com/problems/missing-number/description/
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*
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* algorithms
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* Easy (47.60%)
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* Total Accepted: 267.7K
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* Total Submissions: 556.2K
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* Testcase Example: '[3,0,1]'
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*
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* Given an array containing n distinct numbers taken from 0, 1, 2, ..., n,
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* find the one that is missing from the array.
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*
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* Example 1:
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*
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*
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* Input: [3,0,1]
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* Output: 2
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*
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*
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* Example 2:
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*
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*
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* Input: [9,6,4,2,3,5,7,0,1]
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* Output: 8
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*
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*
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* Note:
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* Your algorithm should run in linear runtime complexity. Could you implement
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* it using only constant extra space complexity?
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*/
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/**
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* @param {number[]} nums
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* @return {number}
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*/
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var missingNumber = function(nums) {
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// 缺失的数字一定是 0 到 n 之间的一个数字
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// 这是一道数论的题目
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// 这里用到了一条性质： sum([1,n]) = n * (n+1) / 2
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let sum = 0;
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for(let num of nums)
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sum += num;
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return (nums.length * (nums.length + 1) )/ 2 - sum;
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};
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