[012-013] Solutions

Author: Dean Strelau

Diff for: data/013

@@ -0,0 +1,100 @@
+37107287533902102798797998220837590246510135740250
+46376937677490009712648124896970078050417018260538
+74324986199524741059474233309513058123726617309629
+91942213363574161572522430563301811072406154908250
+23067588207539346171171980310421047513778063246676
+89261670696623633820136378418383684178734361726757
+28112879812849979408065481931592621691275889832738
+44274228917432520321923589422876796487670272189318
+47451445736001306439091167216856844588711603153276
+70386486105843025439939619828917593665686757934951
+62176457141856560629502157223196586755079324193331
+64906352462741904929101432445813822663347944758178
+92575867718337217661963751590579239728245598838407
+58203565325359399008402633568948830189458628227828
+80181199384826282014278194139940567587151170094390
+35398664372827112653829987240784473053190104293586
+86515506006295864861532075273371959191420517255829
+71693888707715466499115593487603532921714970056938
+54370070576826684624621495650076471787294438377604
+53282654108756828443191190634694037855217779295145
+36123272525000296071075082563815656710885258350721
+45876576172410976447339110607218265236877223636045
+17423706905851860660448207621209813287860733969412
+81142660418086830619328460811191061556940512689692
+51934325451728388641918047049293215058642563049483
+62467221648435076201727918039944693004732956340691
+15732444386908125794514089057706229429197107928209
+55037687525678773091862540744969844508330393682126
+18336384825330154686196124348767681297534375946515
+80386287592878490201521685554828717201219257766954
+78182833757993103614740356856449095527097864797581
+16726320100436897842553539920931837441497806860984
+48403098129077791799088218795327364475675590848030
+87086987551392711854517078544161852424320693150332
+59959406895756536782107074926966537676326235447210
+69793950679652694742597709739166693763042633987085
+41052684708299085211399427365734116182760315001271
+65378607361501080857009149939512557028198746004375
+35829035317434717326932123578154982629742552737307
+94953759765105305946966067683156574377167401875275
+88902802571733229619176668713819931811048770190271
+25267680276078003013678680992525463401061632866526
+36270218540497705585629946580636237993140746255962
+24074486908231174977792365466257246923322810917141
+91430288197103288597806669760892938638285025333403
+34413065578016127815921815005561868836468420090470
+23053081172816430487623791969842487255036638784583
+11487696932154902810424020138335124462181441773470
+63783299490636259666498587618221225225512486764533
+67720186971698544312419572409913959008952310058822
+95548255300263520781532296796249481641953868218774
+76085327132285723110424803456124867697064507995236
+37774242535411291684276865538926205024910326572967
+23701913275725675285653248258265463092207058596522
+29798860272258331913126375147341994889534765745501
+18495701454879288984856827726077713721403798879715
+38298203783031473527721580348144513491373226651381
+34829543829199918180278916522431027392251122869539
+40957953066405232632538044100059654939159879593635
+29746152185502371307642255121183693803580388584903
+41698116222072977186158236678424689157993532961922
+62467957194401269043877107275048102390895523597457
+23189706772547915061505504953922979530901129967519
+86188088225875314529584099251203829009407770775672
+11306739708304724483816533873502340845647058077308
+82959174767140363198008187129011875491310547126581
+97623331044818386269515456334926366572897563400500
+42846280183517070527831839425882145521227251250327
+55121603546981200581762165212827652751691296897789
+32238195734329339946437501907836945765883352399886
+75506164965184775180738168837861091527357929701337
+62177842752192623401942399639168044983993173312731
+32924185707147349566916674687634660915035914677504
+99518671430235219628894890102423325116913619626622
+73267460800591547471830798392868535206946944540724
+76841822524674417161514036427982273348055556214818
+97142617910342598647204516893989422179826088076852
+87783646182799346313767754307809363333018982642090
+10848802521674670883215120185883543223812876952786
+71329612474782464538636993009049310363619763878039
+62184073572399794223406235393808339651327408011116
+66627891981488087797941876876144230030984490851411
+60661826293682836764744779239180335110989069790714
+85786944089552990653640447425576083659976645795096
+66024396409905389607120198219976047599490197230297
+64913982680032973156037120041377903785566085089252
+16730939319872750275468906903707539413042652315011
+94809377245048795150954100921645863754710598436791
+78639167021187492431995700641917969777599028300699
+15368713711936614952811305876380278410754449733078
+40789923115535562561142322423255033685442488917353
+44889911501440648020369068063960672322193204149535
+41503128880339536053299340368006977710650566631954
+81234880673210146739058568557934581403627822703280
+82616570773948327592232845941706525094512325230608
+22918802058777319719839450180888072429661980811197
+77158542502016545090413245809786882778948721859617
+72107838435069186155435662884062257473692284509516
+20849603980134001723930671666823555245252804609722
+53503534226472524250874054075591789781264330331690

Diff for: euler.clj

@@ -79,6 +79,17 @@
 (defn diagonalsr [m]
   (-> m reverse vec diagonals))
 
+(defn find-first [f coll] (first (filter f coll)))
+
+(def triangle-numbers
+  (map #(reduce + (range 1 %)) (iterate inc 1)))
+
+(defn divisors [n]
+  (distinct (flatten (for [f1 (range 1 (inc (Math/sqrt n)))
+        :let [f2 (int (/ n f1))]
+        :when (zero? (mod n f1))]
+    [f1 f2]))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ; 001: Find the sum of all the multiples of 3 or 5 below 1000.
@@ -135,6 +146,18 @@
     (reduce max (map adjmax
       [grid (transpose grid) (diagonals grid) (diagonalsr grid)]))))
 
+; 012: What is the first triangle number to have over 500 divisors?
+(euler 12
+  (find-first #(> (count (divisors %)) 500) triangle-numbers))
+
+; 013: What are the first ten digits of the sum of 100 50-digit numbers?
+(euler 13
+  (let [data (readlines "data/013")
+        nums (map read-string data)
+        sum (apply + nums)
+        take-ten #(apply str (take 10 %))]
+    (take-ten (str sum))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (let [args (seq *command-line-args*)]
   (solve (map #(Integer. %) (or args (range 1 11)))))