Day 7, needed a bit of help figuring out my rounding issues

d07/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "d07"
+version = "0.1.0"

d07/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "d07"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

d07/src/main.rs

@@ -0,0 +1,54 @@
+mod utils;
+
+// const SAMPLE_INPUT: &str = "16,1,2,0,4,2,7,1,2,14";
+const INPUT: &str = "1101,1,29,67,1102,0,1,65,1008,65,35,66,1005,66,28,1,67,65,20,4,0,1001,65,1,65,1106,0,8,99,35,67,101,99,105,32,110,39,101,115,116,32,112,97,115,32,117,110,101,32,105,110,116,99,111,100,101,32,112,114,111,103,114,97,109,10,3,443,2,394,403,176,454,60,126,959,781,426,212,194,65,26,100,1047,718,29,1124,515,723,74,969,717,228,50,39,1074,1799,1276,505,477,9,742,804,191,133,730,26,272,139,501,549,318,1164,1019,399,2,224,1807,421,191,594,168,336,13,271,571,385,1071,1316,1796,673,417,1518,1152,196,1307,262,217,167,696,64,84,844,312,1770,371,517,11,450,745,80,382,367,1527,79,1002,878,298,147,57,24,1282,291,338,911,60,622,508,513,53,404,339,672,440,168,1302,246,116,446,502,1402,398,1686,118,600,865,131,48,162,1614,255,1104,1379,85,115,38,9,483,629,28,157,238,727,27,142,766,716,393,19,115,220,1103,397,1330,1027,667,0,678,464,1431,549,976,456,1403,683,749,600,711,159,98,1000,606,478,428,612,790,1202,1461,713,533,1643,53,29,1,261,268,466,478,187,256,134,373,1239,17,727,574,1206,854,88,27,51,544,793,100,1146,49,166,317,325,506,64,3,255,951,747,274,926,664,531,72,443,1088,91,259,725,100,41,1709,239,101,119,1472,437,91,360,539,96,498,78,825,103,621,216,274,402,133,446,263,1167,212,607,1596,17,113,814,528,56,128,388,686,1179,43,886,58,633,33,186,808,220,98,15,947,1074,612,328,979,1203,562,938,207,35,484,812,616,218,207,249,117,136,39,914,951,122,252,23,1,194,132,366,1004,4,1079,832,510,103,1024,203,398,1543,17,995,961,195,79,1070,1222,53,143,91,223,6,645,175,512,424,471,829,153,126,332,586,543,460,594,105,122,220,432,197,243,73,121,454,765,99,186,35,478,113,1526,305,596,102,365,38,1053,628,24,425,962,570,170,457,268,518,339,32,78,600,8,154,530,641,1889,74,58,1047,166,100,923,687,1280,1144,1260,405,1786,22,694,243,284,1109,503,650,633,52,236,661,620,54,642,130,697,718,259,244,52,387,347,459,724,661,535,354,53,105,246,493,538,894,0,368,67,151,2,127,724,705,237,512,557,573,829,789,61,415,131,526,982,206,73,46,82,411,1670,1350,34,654,190,160,575,669,21,830,34,1233,371,819,360,271,173,420,38,112,273,115,493,40,51,634,844,281,613,193,10,111,567,52,17,1137,117,105,122,250,72,70,1038,210,1008,191,99,1123,1641,90,1306,47,385,835,395,1057,1036,4,127,103,486,205,138,929,286,46,641,1041,490,399,178,1492,421,106,275,741,1196,15,174,700,892,8,818,215,436,624,459,415,812,28,196,921,119,333,896,541,117,926,1084,276,222,361,325,23,1295,205,384,207,863,659,22,89,21,110,269,157,385,422,941,629,1511,544,701,404,489,38,495,507,238,132,753,119,459,145,120,984,313,973,1049,158,372,317,596,1024,177,256,23,6,527,1439,592,743,104,414,256,418,425,271,58,583,0,164,277,1285,809,125,391,843,70,69,194,250,611,287,2,389,1469,555,552,28,236,278,178,314,368,254,86,240,72,204,8,856,28,312,236,464,144,405,433,28,42,16,587,22,403,1234,744,484,48,180,238,47,384,1315,13,78,9,882,70,551,58,756,111,777,340,1046,185,83,412,19,527,514,355,350,1198,913,154,87,507,76,1108,392,361,1081,75,1083,201,896,1161,1267,46,420,79,702,879,348,622,68,611,180,515,37,186,435,1485,438,699,1441,1122,85,145,1372,68,2,621,147,503,156,993,496,536,359,485,657,152,585,681,908,294,398,4,190,33,197,304,157,38,77,922,1033,166,85,411,544,1688,81,192,111,561,212,176,291,44,76,465,35,6,110,1329,1702,53,70,82,4,1141,278,483,66,9,115,733,856,18,1167,282,100,11,605,673,1093,1268,1633,1632,570,847,575,160,8,335,5,27,489,3,1669,1072,571,144,460,15,200,15,108,473,527,775,818,87,359,46,665,191,635,1122,289,457,169,17,42,395,1258,189,253,1292,69,370,419,47,79,22,668,655,274,60,1012,428,246,248,1181,520,760,1274,320,608,65,137,722,386,275,252,1221,729,421,265,171,84,9,3,8,1328,86,939,890,986,34,156,245,1896,617,1733,346,751,1281,244,346,56,196,380,426,810,233,353,28,147,307,131,1529,1173,68,862,1048,774,571,699,163,306,385,368,150,651,316,517,47,508,407,452,315,257,1652,73,222,1187,1635,1268,48,301,247,308,211,149,1300,141,113,57,152,498,450,34,376,748,442,670,358,105,587,66,0,285,46";
+
+fn part1(input: &str) {
+    let mut crab_positions: Vec<usize> = utils::parse_delimited(input, ",");
+    println!(
+        "Initial crab positions {}",
+        utils::join_vec(";", &crab_positions)
+    );
+    crab_positions.sort();
+
+    let median = crab_positions[crab_positions.len() / 2];
+    println!("Median is {}", median);
+
+    let result: usize = crab_positions
+        .iter()
+        .map(|p| (*p as isize - median as isize).abs() as usize)
+        .sum();
+
+    println!("Part 1 fuel use is {}", result);
+}
+
+fn part2(input: &str) {
+    let crab_positions: Vec<i32> = utils::parse_delimited(input, ",");
+    println!(
+        "Initial crab positions {}",
+        utils::join_vec(";", &crab_positions)
+    );
+
+    let old_mean: f32 =
+        crab_positions.iter().map(|v| *v as f32).sum::<f32>() / crab_positions.len() as f32;
+
+    // This needs to be floored rather than rounded up. I think I should have compared this to the
+    // median and rounded in that direction to minimize change after rounding
+    println!("Old mean is {}", old_mean);
+
+    let mean: i32 = crab_positions.iter().sum::<i32>() / crab_positions.len() as i32;
+    println!("Mean value is {}", mean);
+
+    // This part is ok
+    let result: usize = crab_positions
+        .iter()
+        .map(|p| (*p as isize - mean as isize).abs() as usize)
+        .map(|d| (0..d + 1).sum::<usize>())
+        .sum();
+    println!("Part 2 fuel use is {}", result);
+}
+
+fn main() {
+    part1(INPUT);
+    part2(INPUT);
+}

d07/src/utils.rs

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+use std::fmt;
+use std::str::FromStr;
+
+/// Returns a vector of items parsed from a delimited string
+///
+/// # Arguments
+///
+/// * `input` input string to split and parse from
+/// * `delimiter` item delimiter
+pub fn parse_delimited<T>(input: &str, delimiter: &str) -> Vec<T>
+where
+    T: FromStr,
+    <T as FromStr>::Err: fmt::Debug,
+{
+    input
+        .split(delimiter)
+        .map(|v| {
+            v.trim()
+                .parse::<T>()
+                .expect(format!("Unable to parse '{}' from text '{}'", v, input).as_str())
+        })
+        .collect()
+}
+
+/// Returns a string with each element of the vector formatted and joined
+///
+/// # Arguments
+///
+/// * `join_str` the string to use to join the vector elements
+/// * `v` the vector with elements to join
+pub fn join_vec<T: std::fmt::Display>(join_str: &str, v: &Vec<T>) -> String {
+    v.iter()
+        .map(|p| format!("{}", p))
+        .collect::<Vec<String>>()
+        .join(join_str)
+}