以下为时间: // (all __int64) to compute the 7 * 7 it took 191.344000 seconds // (all __int64) and find the correct answer = 61479419904000 . // (all __int64) after delete the print for ans % 1000000 275.672000 seconds // actually only ans is needed to be __int64 for 7 * 7 and the time needed is // 115.735000 seconds ,the best since . // again and 119.797000 seconds;