合聚咖

合聚咖

设有长度为1,2,3,4,5,6,7,8,9的木棒若干条,从这些木棒中选取三条组成一个三角形,共有多少种不同的方法

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95种,如下:

111,122,133,144,155,166,177,188,199

222,223,233,234,244,245,255,256,266,267,277,278,288,289,299

333,,334,335,344,345,346,355,356,357,366,367,368,377,378,379,388,389,399

444,445,446,447,455,456,457,458,466,467,468,469,477,478,479,488,489,499

555,556,557,558,559,566,567,568,569,577,578,579,588,589,599

666,667,668,669,677,678,679.,688,689,699

777,778,779,788,789,799

888,889,899

999