( 设计高效算法 ) 年龄排序 Age Sort Uva 11462

可以使用整数排序法, 内存太小无法堆排序.

#include <cstdio>
#include <cstring>
using namespace std;

int main(){
	unsigned int age[101];
	int n,temp;

	while (scanf("%d", &n) == 1 && n){
		memset(age, 0, sizeof(age));
		for (int i = 0; i < n; i++){
			scanf("%d", &temp);
			age[temp]++;
		}
		bool first = 1;
		for (int i = 1; i < 101; i++){
			for (int j = 0; j < age[i];j++)
			{
				if (!first) printf("");
				else first = false;
				printf("%d", i);
			}
		}
		printf("\n");
	}

}

优化输入输出也可以提高效率, 但是这个是最后考虑的优化要素.

函数名前 的inline 相当于c的宏定义, 降低大量函数引用消耗的时间.

使用cctype 中的 isdigit

#include <cstdio>
#include <cstring>
#include <cctype>
using namespace std;

inline int readint(){
	char c = getchar();
	while (!isdigit(c)) c = getchar();
	unsigned int num = 0;
	while (isdigit(c)){
		num = num * 10 + c - '0';
		c = getchar();
	}
	return num;
}

inline void writeint(unsigned int i){
	char buf[10];
	int p = 0;
	while (i){
		buf[p++] = i % 10;
		i /= 10;
	}
	for (int j = p - 1; j >= 0; j++) putchar('0' + buf[j]);
}




int main(){
	int n;
	int age[101];
	while (n = readint()){
		memset(age, 0, sizeof(age));
		for (int i = 0; i < n; i++){
			age[readint()]++;
		}
		bool first = true;
		for (int i = 1; i < 101; i++){
			for (int j = 0; j < age[i]; j++){
				if (!first) putchar(' ');
				else first = false;
				writeint(i);
			}
		}
		putchar('\n');
	}
}