Leetcode题解 268. Missing Number

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Given an array containing n distinct numbers taken from 0, 1, 2, …, n, find the one that is missing from the array.

For example,
Given nums = [0, 1, 3] return 2.

解法一：（用等差数列的做法）

public class Solution {    public int missingNumber(int[] nums) {        int sum=nums.length*(nums.length+1)/2;        for(int i=0;i<nums.length;i++){            sum-=nums[i];        }        return sum;    }}

解法二，位运算

public class Solution {    public int missingNumber(int[] nums) {        int sum=0;        for(int i=1;i<=nums.length;i++){            sum^=i;        }        for(int i=0;i<nums.length;i++){            sum^=nums[i];        }        return sum;    }}

解法三，位运算的更简洁写法

public class Solution {    public int missingNumber(int[] nums) {        int sum=0;        for(int i=1;i<=nums.length;i++){            sum^=i;            sum^=nums[i-1];        }        return sum;    }}

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