Added day 7

source/app.d

@@ -1,7 +1,7 @@
 import std.stdio;
 
-import day6.part1;
+import day7.part1;
 
 void main() {
-	lanternFish();
+	crabFuel();
 }

source/day7/input.txt

@@ -0,0 +1 @@
+1101,1,29,67,1102,0,1,65,1008,65,35,66,1005,66,28,1,67,65,20,4,0,1001,65,1,65,1106,0,8,99,35,67,101,99,105,32,110,39,101,115,116,32,112,97,115,32,117,110,101,32,105,110,116,99,111,100,101,32,112,114,111,103,114,97,109,10,807,891,601,565,31,61,126,1220,923,21,750,38,834,1494,1187,235,138,344,438,1078,1664,936,451,86,34,292,782,923,154,1060,286,713,1557,1693,95,7,263,1100,402,472,342,384,95,968,319,193,1130,983,100,88,1020,720,693,790,113,30,30,759,151,1039,111,172,46,478,341,182,229,96,750,88,254,105,599,1074,20,366,307,286,25,467,927,1000,898,139,757,20,13,51,284,323,271,26,93,178,354,1016,165,39,1243,383,89,141,52,260,831,681,189,439,8,4,1849,272,1904,377,422,468,193,81,204,8,1165,919,16,404,442,1571,124,76,534,323,43,16,1039,68,203,177,60,963,100,34,35,433,17,14,432,60,835,789,191,248,256,68,367,326,1271,329,23,992,156,627,365,798,154,457,71,489,3,403,1138,23,1085,128,124,270,65,279,564,145,612,412,700,387,598,7,125,764,1456,1433,1010,874,262,3,39,3,157,280,182,1,1534,49,237,873,585,424,870,93,406,4,343,956,207,271,727,62,376,35,49,74,1532,1318,11,637,398,1508,143,200,339,331,14,447,121,886,512,0,79,246,1292,269,71,83,126,124,120,38,430,238,311,460,549,544,1050,421,421,67,82,25,1730,134,923,161,417,178,1730,81,34,921,1283,648,149,76,390,1311,677,182,184,1109,576,1079,569,136,106,35,1205,170,216,908,523,54,80,87,1278,1080,885,1028,423,310,71,183,395,1269,268,356,628,1173,1026,816,715,751,231,31,86,625,1231,310,86,226,405,111,991,261,145,487,196,183,234,346,987,268,28,299,40,313,597,387,44,648,134,78,302,1189,898,56,957,175,193,170,186,170,7,1789,8,632,503,587,229,72,286,522,145,653,5,29,31,486,145,258,784,513,341,331,223,387,986,374,512,1074,80,119,369,557,57,18,66,1113,251,151,319,138,485,623,577,398,487,281,113,864,273,30,29,1184,194,1531,503,147,402,1587,525,288,1015,921,601,53,346,972,646,151,163,61,585,242,67,258,36,586,347,322,341,251,112,1250,70,35,36,110,392,44,60,401,34,563,374,977,252,184,384,84,912,215,1198,176,630,708,791,1622,343,454,576,218,1054,118,14,10,665,551,20,259,497,289,176,72,524,4,147,1323,596,1512,104,278,332,283,43,804,326,258,247,776,665,435,1683,286,516,677,287,1227,409,411,49,425,207,78,157,487,364,727,976,347,158,292,28,139,1040,217,256,1385,600,95,339,32,64,53,31,394,154,281,1334,161,1291,1474,13,453,1461,25,272,594,832,473,1117,207,1107,595,732,1284,77,504,154,960,191,1416,429,587,654,457,462,457,697,45,366,960,1486,273,747,1366,389,453,1278,852,221,950,537,29,109,1052,112,331,349,790,903,215,135,1457,63,997,8,226,1440,587,1044,215,152,317,336,71,52,1612,438,218,1818,220,186,388,654,93,450,915,1083,145,69,296,712,185,569,849,236,1884,117,761,136,1260,319,1553,751,275,181,137,144,222,322,387,38,951,510,1051,614,1819,436,430,1425,8,271,387,19,205,215,21,585,462,798,27,1512,279,831,1113,97,371,998,677,1488,125,5,208,417,912,1083,276,39,919,91,29,182,1727,650,49,727,1389,1389,23,725,1109,890,594,397,246,47,520,305,282,81,157,283,1031,65,1355,773,480,0,162,655,46,786,677,394,506,1581,1011,149,248,107,212,446,163,553,1005,1,856,32,34,682,128,328,114,7,737,188,31,1157,590,397,159,366,449,601,225,121,320,163,849,746,122,141,443,616,72,660,244,964,718,1628,77,129,854,206,12,458,1130,207,26,622,502,934,979,577,611,1187,62,981,1692,38,11,85,1417,1152,1846,520,1001,104,595,586,945,8,624,1043,955,262,53,453,377,234,1363,239,1553,760,641,615,784,633,1289,853,1224,834,488,521,71,510,45,41,309,50,245,423,7,520,350,137,275,429,86,144,800,172,214,679,87,321,682,1005,278,518,330,705,613,818,1014,469,98,581,72,1647,165,25,510,369,1013,598,209,6,323,530,59,41,1266,787,1191,149,213,8,1490,105,288,88,607,556,50,17,76,513,717,1236,1532,1455,23,77,472,573,303,0,419,573,1217,1,144,648,95,326,999,1359,324,172,259,516,1178,84,1030,73,12,867,1477,70,147,317,999,1377,196,342,127,787,372,687,855,5,1663,49,552,380,95,469,132,58,397,213,194,35,1353,216,12,497,610,571,802,392,42,490,778,6,483,1451

source/day7/part1.d

@@ -0,0 +1,23 @@
+module day7.part1;
+
+import std.stdio;
+import std.math;
+import std.algorithm;
+import util.fileutils;
+
+int getFuelCost(int[] crabs, int pos) {
+    return crabs.map!((crab) {
+        int distance = abs(pos - crab);
+        return (distance * (distance + 1)) / 2;
+    }).sum();
+}
+
+void crabFuel() {
+    int[] crabs = readInts("source/day7/input.txt", ",");
+    int minCost = 1_000_000_000;
+    foreach (pos; crabs.minElement .. crabs.maxElement) {
+        int c = getFuelCost(crabs, pos);
+        if (c < minCost) minCost = c;
+    }
+    writefln("%d", minCost);
+}

source/day7/test_input.txt

@@ -0,0 +1 @@
+16,1,2,0,4,2,7,1,2,14

source/util/fileutils.d

@@ -12,11 +12,12 @@ import std.conv;
  *   filename = The name of the file to read, relative to the working dir.
  * Returns: A list of integers.
  */
-int[] readInts(string filename) {
-    return readText("source/day1/input.txt")
-        .split("\n")
+int[] readInts(string filename, string sep = "\n") {
+    return readText(filename)
+        .strip()
+        .split(sep)
         .map!(s => s.strip())
         .filter!(s => s.length > 0)
         .map!(s => s.to!int)
         .array;
-}
+}