算法学习

值得反复回味的代码

1.用100换1，2，5，10

'''
用100换1，2，5，10
或者用一个大数N换几个小数x1,x2,x3,x4...xn，的换法
'''

numarr=[1,2,5,10]    #可以改变
res =[0 for x in range(0,101)]
res[0] = 1
i =0
for j in range(len(numarr)):
    for i in range(numarr[j],101):
        #核心递推公式
        #采用的是动态规划
        res[i]+=res[i-numarr[j]]
    print res
print max(res)

''‘’
最终res的结果：
[1, 1, 2, 2, 3, 4, 5, 6, 7, 8, 11, 12, 15, 16, 19, 22, 25, 28, 31, 34, 40, 43, 49, 52, 58, 64, 70, 76, 82, 88, 98, 104, 114, 120, 130, 140, 150, 160, 170, 180, 195, 205, 220, 230, 245, 260, 275, 290, 305, 320, 341, 356, 377, 392, 413, 434, 455, 476, 497, 518, 546, 567, 595, 616, 644, 672, 700, 728, 756, 784, 820, 848, 884, 912, 948, 984, 1020, 1056, 1092, 1128, 1173, 1209, 1254, 1290, 1335, 1380, 1425, 1470, 1515, 1560, 1615, 1660, 1715, 1760, 1815, 1870, 1925, 1980, 2035, 2090, 2156]
'''

2.输出连输子数组的最大和

#最大子数组和
a = [1,-2,3,5,1,8,2,-2,5,-6,3,2]
maxarr=[0 for x in range(len(a))]
currsum=0
maxarr[0]=a[0]
max1=a[0]
print 'currsum:',
for i in range(0,len(a)):
    if currsum>=0:
        currsum +=a[i]
    else:
        currsum = a[i]
    if max1<currsum:
        max1=currsum
    maxarr[i]=max1
    print currsum,
print
print maxarr
print max(maxarr)
'''
输出结果：
currsum: 1 -1 3 8 9 17 19 17 22 16 19 21
[1, 1, 3, 8, 9, 17, 19, 19, 22, 22, 22, 22]
22
'''