尤拉計劃問題八matlab實現
problem 8 :Largest product in a series
The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.
73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450
Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?
思路 :
題目的意思是這是一個1000位的數,其中相鄰的四位數相乘所得最大的數為5832,現在讓我們求相鄰的十三位數相乘所得最大的數是多少?
首先我們從題目的那個例子裡思考入手,應該是迴圈相乘比較,並求出最大得數。我們思考問題可以由易到難,我們假設有一個十位數的數,隨便寫一個十位數的數--------5265659989,接下來我們設計一下程式的演算法,畫一張圖解:
這是一個十位數的數,我們求相鄰四位數相乘所得的最大數,相當於我們將其分割為6個塊(相當於1到10-4+1),設定一個變數max,首先將其賦值為0,迴圈變數 i 從1到10-4+1,譬如第一次算第一位乘到第四位(5x2x6x5)的值賦給變數value, 每算出一次value,將其與max比較,若value大於max,就將value的值賦值給max,否則就繼續執行下一次,這樣我們最後得到的max就是最大值輸出。完了謝謝!
程式碼 :
%Problem 8 tic w = '7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450'; %%just copy the numbers to here max = 0; %initial value value = 1; %initial value for i = 1:988 n1 = str2double(w(i)); n2 = str2double(w(i+1)); n3 = str2double(w(i+2)); n4 = str2double(w(i+3)); n5 = str2double(w(i+4)); n6 = str2double(w(i+5)); n7 = str2double(w(i+6)); n8 = str2double(w(i+7)); n9 = str2double(w(i+8)); n10 = str2double(w(i+9)); n11= str2double(w(i+10)); n12 = str2double(w(i+11)); n13 = str2double(w(i+12)); value = n1*n2*n3*n4*n5*n6*n7*n8*n9*n10*n11*n12*n13; if value > max max = value; %update the value of max end end disp(max) toc
結果 : 2.351462400000000e+10
關於結果的輸出這裡你需要在matlab的選單欄裡找到Preferences--->Command Windows,找到右邊的Text display,將Numeric format中的short改為long e。
小結 :
希望大家多多交流,互相學習!