1 #define _for(i,a,b) for(int i = (b)-1;i >= (a);i --) 2 class Solution 3 { 4 public: 5 int hash[10] {0}; 6 string result; 7 int dfs(int pos,int limit) 8 { 9 if(pos==4) 10 return 1; 11 else if(pos==0) 12 { 13 _for(i,0,3) 14 { 15 if(hash[i]) 16 { 17 if(i==2) 18 { 19 result += '2'; 20 hash[2] --; 21 int st = dfs(1,1); 22 if(st) 23 return 1; 24 result.pop_back(); 25 hash[2] ++; 26 } 27 else 28 { 29 result += i+'0'; 30 hash[i] --; 31 int st = dfs(1,0); 32 if(st) 33 return 1; 34 result.pop_back(); 35 hash[i] ++; 36 } 37 } 38 } 39 } 40 else if(pos==1 && limit==0) 41 { 42 _for(i,0,10) 43 { 44 if(hash[i]) 45 { 46 result += i+'0'; 47 hash[i] --; 48 int st = dfs(2,0); 49 if(st) 50 return 1; 51 result.pop_back(); 52 hash[i] ++; 53 } 54 } 55 } 56 else if(pos==1 && limit==1) 57 { 58 _for(i,0,4) 59 { 60 if(hash[i]) 61 { 62 result += i+'0'; 63 hash[i] --; 64 int st = dfs(2,1); 65 if(st) 66 return 1; 67 result.pop_back(); 68 hash[i] ++; 69 } 70 } 71 } 72 else if(pos==2) 73 { 74 _for(i,0,6) 75 { 76 if(hash[i]) 77 { 78 result += i+'0'; 79 hash[i] --; 80 int st = dfs(3,limit); 81 if(st) 82 return 1; 83 result.pop_back(); 84 hash[i] ++; 85 } 86 } 87 } 88 else if(pos==3) 89 { 90 _for(i,0,10) 91 { 92 if(hash[i]) 93 { 94 result += i+'0'; 95 hash[i] --; 96 int st = dfs(4,limit); 97 if(st) 98 return 1; 99 result.pop_back(); 100 hash[i] ++; 101 } 102 } 103 } 104 return 0; 105 } 106 string largestTimeFromDigits(vector<int>& A) 107 { 108 hash[A[0]] ++; 109 hash[A[1]] ++; 110 hash[A[2]] ++; 111 hash[A[3]] ++; 112 int st = dfs(0,0); 113 if(st) 114 { 115 string rnt = ""; 116 rnt += result[0]; 117 rnt += result[1]; 118 rnt += ':'; 119 rnt += result[2]; 120 rnt += result[3]; 121 return rnt; 122 } 123 else 124 { 125 string a = ""; 126 return a; 127 } 128 return result; 129 } 130 };
慌了