剑指offer——丑数

#include <iostream>
#include <cmath>
#include <vector> 
using namespace std;

class Solution {
    public:
        int GetUglyNumber_Solution(int index) {
            if(index < 7){
                return index;
            }
            vector<int> ans(index);
            ans[0] = 1;
            int t2 = 0,t3 = 0,t5 = 0;
            for(int i = 1 ; i < index ; i++){
                ans[i] = min(ans[t2]*2,min(ans[t3]*3,ans[t5]*5));
                if(ans[t2]*2 == ans[i]){
                    t2++;
                }
                if(ans[t3]*3 == ans[i]){
                    t3++;
                }
                if(ans[t5]*5 == ans[i]){
                    t5++;
                }
            }
            return ans[index-1];
        }
};