Ugly Numbers UVA - 136

Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, ...shows the first 11 ugly numbers. By convention, 1 is included.Write a program to find and print the 1500’th ugly number.InputThere is no input to this program.OutputOutput should consist of a single line as shown below, with ‘’ replaced by the numbercomputed.Sample OutputThe 1500'th ugly number is .

题意:定义丑数是不能被2,3,5意外的其他素数整除的数;求第1500个丑数

题解:建立优先队列,每出来一个丑数塞三个丑数回去

代码:

#pragma comment(linker, "/STACK:102400000,102400000") 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define Pi acos(-1.0)
using namespace std;
typedef long long ll;
int a[3] = {2,3,5};
mapmp;
int main(){
	mp.clear();
	priority_queue, greater >que;
	que.push(1);
	mp[1] = 1;
	for(int i = 1;;i++){
		ll now = que.top();
		que.pop();
		if(i==1500){
			printf("The 1500'th ugly number is %lld.\n", now);
			break;
		}
		for(int j = 0;j < 3;j++){
			ll nnow = now * a[j];
			if(!mp[nnow]){
				mp[nnow] = 1;
				que.push(nnow);
			}
		}
		
	}
}

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