LeetCode--179场周赛题解

水题：

 class Solution {
 public:
     string generateTheString(int n) {
     string s;
     string a="a",b="b";
     if( n%==){

         for(int i =; i <= n - ; i++)
             s = s + a;
         s = s + b;
     }
     else{
         for(int i =; i <= n ; i++)
             s = s + a;
     }
         return s;
     }
 };

难题：1377. T 秒后青蛙的位置

思路：自底向上反推，从结果入手寻找答案

 #include<string.h>
 class Solution {
 public:
     double frogPosition(int n, vector< vector<int> >& edges, int t, int target) {

         int a[];
         int step = t;
         double ans = ;
         memset(a, , sizeof(a) );
         if (edges.size() ==  ){
             return ;
         }
         else if ( target == ) {
             return ;
         }

          for (int i = ; i < edges.size(); i++){
              if (edges[i][]>edges[i][]){
                  swap(edges[i][],edges[i][]);
              }
              a[edges[i][]]++;

         }

         int flag = a[target];

         while(){
             for (int i = ; i < edges.size(); i++) {

                 if ( edges[i][] == target){

                         target = edges[i][];
                         ans = ans /a[edges[i][]];
                         t--;

                         if (target == ) {
                             if ( t == )  return ans;
                             else if (t >  && flag == ) return ans;
                             else return ;
                         }
                     break;

                  }

             }
         }
     }
 };