That's a simple MATH problem

  • 1

    I think we can take this problem as a MATH problem, the sum should be (n+0)*(n+1)/2, then minus each of the element in the array.

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

  • 0

    what if the sum overflows?

  • 0

    yes. it may overflow. you must use bit operation or use string adder

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