HDU - 1058
简单dp,问因子只含有2,3,5,7的第k个数是什么?
直接4个dp数组循环
#include <iostream> #include <cstdio> #include <math.h> #include <cmath> #include <algorithm> using namespace std; #define ll long long int dp[5845]; void init() { int a,b,c,d; a = b = c = d = 1; dp[1] = 1; for(int i=2 ;i<=5842;i++) { dp[i] = min(dp[a]*2, min(dp[b]*3, min(dp[c]*5,dp[d]*7))); if(dp[i] == dp[a]*2) a++; if(dp[i] == dp[b]*3) b++; if(dp[i] == dp[c]*5) c++; if(dp[i] == dp[d]*7) d++; } } int main() { init(); int n; while(scanf("%d",&n)!=EOF&&n) { cout<<"The "<<n; if(n%10 == 1&&n%100 != 11) cout<<"st "; else if(n%10 == 2&&n%100 != 12) cout<<"nd "; else if(n%10 == 3&&n%100 != 13) cout<<"rd "; else cout<<"th "; cout<<"humble number is "<<dp[n]<<"."<<endl; } return 0; }