【每日算法Day 75】字节跳动面试题：手撕困难题，看过我Day 71的人都会做了！

classSolution {
public:  
intfirstMissingPositive(vector<int>&nums) { 
intn=nums.size();  
nums.push_back(-1);  
for (inti=0; i<=n; ++i) {  
if (nums[i] <=0||nums[i] >n) {   
nums[i] =-1;  
            }    
        }    
for (inti=0; i<=n; ++i) {   
while (nums[i] !=-1&&i!=nums[i] &&nums[i] !=nums[nums[i]]) {  
swap(nums[i], nums[nums[i]]);    
            }        
if (nums[i] !=-1&&i!=nums[i]) {   
nums[i] =-1;  
            }  
        }     
for (inti=1; i<=n; ++i) {      
if (nums[i] ==-1) returni; 
        }      
returnn+1;    
    }
};