高速ãªç´¯ä¹—計算 - ã‚ã©ã‘ãªã„話累乗(x^n)ã‚’å˜ç´”ã«è¨ˆç®—ã™ã‚‹ã¨ã€ã‚ªãƒ¼ãƒ€ãƒ¼ã¯ O(n)ã¨ãªã‚ŠåŠ¹çŽ‡ãŒæ‚ªã„ã§ã™ã€‚ãã“ã§ã€nã‚’2ã®ç´¯ä¹—ã«åˆ†è§£ã—ã¦è¨ˆç®—ã™ã‚‹é«˜é€ŸåŒ–手法ãŒä¸€èˆ¬ã«çŸ¥ã‚‰ã‚Œã¦ã„ã¾ã™ã€‚ ãŸã¨ãˆã°ã€3 ã® 11 乗を計算ã™ã‚‹å ´åˆã‚’考ãˆã¾ã—ょã†ã€‚11 㯠1 + 2 + 8 ã«åˆ†è§£ã§ãã¾ã™ã€‚ ã“ã®ç´¯ä¹—ã®ç³»åˆ—ã§ã¯ã€ã‚る値ã¯ä¸€ã¤å‰ã®å€¤ã‚’2ä¹—ã™ã‚‹ã“ã¨ã§è¨ˆç®—ã§ãã¾ã™ã€‚ãŸã¨ãˆã°ã€ã“ã†ã§ã™ã€‚ 3^1 = 3 3^2 = 3 * 3 = 9 3^4 = (3^2)^2 = 9^2 = 81 3^8 = (3^4)^2 = 81^2 = 6561よã£ã¦ã€3^11 ã¯ä»¥ä¸‹ã®ã‚ˆã†ã«è¨ˆç®—ã§ãã¾ã™ã€‚ 3^11 = 3^(1+2+8) = 3^1 × 3^2 × 3^8 = 3 × 9 × 6561 = 177147ã“ã®æ–¹æ³•ã®ã‚ªãƒ¼ãƒ€ãƒ¼ã¯ã€O(log2(n)) ã§ã™ã€‚ é…延評価風㫠RSA ã®ãŸã‚ã«é«˜é€Ÿãªç´¯ä¹—計算を Haskell ã§å®Ÿè£…ã—ãŸã“ã¨ãŒã‚ã‚Šã¾ã—
{{#tags}}- {{label}}
{{/tags}}