不对,除了1和100..2和99,100.3和98,99,100.49和52,53,...100.的1+2+3+...+49=1225种. 还有50和51,52,...100.51和52,53,...100.97和98,99,100.98和99,100.99和100.的50+49+48+...+1=1275种.总共是2500种取法....