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Sum of Factorials

[编程题]Sum of Factorials
  • 热度指数:6125 时间限制:C/C++ 1秒,其他语言2秒 空间限制:C/C++ 64M,其他语言128M
  • 算法知识视频讲解
    John von Neumann, b. Dec. 28, 1903, d. Feb. 8, 1957, was a Hungarian-American mathematician who made important contributions to the foundations of mathematics, logic, quantum physics, meteorology, science, computers, and game theory. He was noted for a phenomenal memory and the speed with which he absorbed ideas and solved problems. In 1925 he received a B.S. diploma in chemical engineering from Zurich Institute and in 1926 a Ph.D. in mathematics from the University of Budapest, His Ph.D. dissertation on set theory was an important contributions to the subject.     At the age of 20, von Neumann proposed a new definition of ordinal numbers that was universally adopted. While still in his twenties, he made many contributions in both pure and applied mathematics that established him as a mathematician of unusual depth. His Mathematical Foundation of Quantum Mechanics (1932) built a solid framework for the new scientific discipline.     During this time he also proved the mini-max theorem of GAME THEORY. He gradually expanded his work in game theory, and with coauthor Oskar Morgenstern he wrote Theory of Games and Economic Behavior (1944).     There are some numbers which can be expressed by the sum of factorials. For example 9, 9 = 1! + 2! + 3! . Dr. von Neumann was very interested in such numbers. So, he gives you a number n, and wants you to tell whether or not the number can be expressed by the sum of some factorials. Well, it is just a piece of case. For a given n, you will check if there are some xi, and let n equal to Σt (上标) i=1(下标) xi! (t≥1, xi≥0, xi = xj <==> i = j)            t      即 Σ  xi! (t≥1, xi≥0, xi = xj <==> i = j)           i=1     If the answer is yes, say "YES"; otherwise, print out "NO".

输入描述:
    You will get a non-negative integer n (n≤1,000,000) from input file.


输出描述:
    For the n in the input file, you should print exactly one word ("YES" or "NO") in a single line. No extra spaces are allowed.
示例1

输入

9
2

输出

YES
YES
while True:
    try:
        num = int(input())
        factor = [1]*10
        for i in range(2,10):        #因为输入最大1000000,所以前十个阶乘就可以了
            factor[i] = factor[i-1]*i
        index = 9
        while index >= 0:            #一直减,能减就减,因为阶乘大于其前面所有阶乘的和
            if num >= factor[index]:
                num -= factor[index]
            index -= 1
        if num == 0:                 #如果减空了说明能分解为阶乘之和
            print('YES')
        else:
            print('NO')
    except Exception:
        break
编辑于 2018-10-14 13:05:18 回复(0)