Given a sorted integer array nums, where the range of elements are in the inclusive range [lower, upper], return its missing ranges.
example:
Input: nums =[0, 1, 3, 50, 75], lower = 0 and upper = 99, Output:["2", "4->49", "51->74", "76->99"]
这题应该是实现的细节处理，最大整数，最小整数比较难，也是调了很久的corner case才调出来的。
好不容易Accept了，自己写的还是有点惨。
还要注意
if(lower++ == something) something;
不管判断对不对，lower都会自增的，要当心。
AC第一版
1 #include <iostream> 2 #include <vector> 3 using namespace std; 4 struct TreeNode { 5 int val; 6 TreeNode *left; 7 TreeNode *right; 8 TreeNode(int x) : val(x), left(NULL), right(NULL) {} 9 }; 10 15 16 17 vector<string> findMissingRanges(vector<int>& nums, int lower, int upper) { 18 vector<string> ret; 19 vector<int> processed; 20 for(int i=0; i<nums.size(); i++){ 21 if(processed.empty() || processed.back() != nums[i]){ 22 processed.push_back(nums[i]); 23 } 24 } 25 nums.clear(); 26 //for(auto i : processed) nums.push_back(i); 27 28 for(auto i : processed) cout << i << " "; 29 cout << endl; 30 nums = processed; 31 if(lower == upper) { 32 if(!nums.empty()) return ret; 33 else ret.push_back(to_string(lower)); 34 return ret; 35 } 36 if(nums.empty()){ 37 ret.push_back(to_string(lower) + "->" + to_string(upper)); 38 return ret; 39 } 40 for(int i=0; i<nums.size(); i++){ 41 //cout << lower << "and" << nums[i] << endl; 42 if (lower == nums[i]) { 43 lower++; 44 continue; 45 } 46 47 if(lower+1 == nums[i]) ret.push_back(to_string(lower)); 48 else ret.push_back(to_string(lower) + "->" + to_string(nums[i]-1)); 49 if(nums[i] == (1 << 31)-1) return ret; 50 lower = nums[i]+1; 51 } 52 //cout << lower << upper << endl; 53 if(lower > upper) return ret; 54 if(lower == upper) ret.push_back(to_string(lower)); 55 else ret.push_back(to_string(lower) + "->" + to_string(upper)); 56 return ret; 57 }
AC 第二版
简化了一些代码
vector<string> findMissingRanges(vector<int>& nums, int lower, int upper) { vector<string> ret; vector<int> processed; // filter duplicate for(auto val : nums) { if(processed.empty() || processed.back() != val) processed.push_back(val); } nums.clear(); nums = processed; // for(auto i : processed) cout << i << " "; // cout << endl; // corner case 1: lower == upper if(lower == upper) { if(nums.empty()) ret.push_back(to_string(lower)); return ret; } for(int i=0; i<nums.size(); i++){ if (lower != nums[i]) { if(lower+1 == nums[i]) ret.push_back(to_string(lower)); else ret.push_back(to_string(lower) + "->" + to_string(nums[i]-1)); } if(nums[i] == (1 << 31)-1) return ret; lower = nums[i]+1; } //cout << lower << upper << endl; if(lower == upper) ret.push_back(to_string(lower)); else if(lower < upper) ret.push_back(to_string(lower) + "->" + to_string(upper)); return ret; }