268. Missing Number

268. Missing Number

class Solution {
public:
int missingNumber(vector<int>& nums) {
int nums_len = nums.size() - 1;

for(int i = 0; i <= nums_len; i++) {
if(abs(nums[i]) <= nums_len && nums[i] != INT_MIN) {
if(!nums[abs(nums[i])])  nums[abs(nums[i])] = INT_MIN;
else  nums[abs(nums[i])] = -1*nums[abs(nums[i])];
}
else if(nums[i] == INT_MIN)
nums[0] = -1*nums[0];
}

for(int j = 0; j <= nums_len; j++)
if(nums[j] >= 0)
return j;

return nums_len + 1;
}
};