# Overview

There are many recurring patterns in my programs.
On this page I explain in my own, non-scientific words, why and how I use them.

(TODO: write more, more, more on this page)

# Caching

The technique I probably use the most is caching:
Whenever a result needs to be computed multiple times and that computation took some time, then I store it in a cache.
Hereby result can be a number, a string or an object. It is stored in a container and accessed via a unique key.

The unique key of an std::vector or std::map is its index.
Even though std::map is much more flexible, I try to avoid it due to its lackluster performance compared to std::vector.

Examples:

# Incremental computation

This is somehow related to caching:
if a program needs to compute multiple results then it's often more efficient to compute those in some order such that we can re-use results from earlier iterations.
In my opinion, Dynamic Programming can be seen as the reversal of incremental computation.

Examples:

# Heatmap

green problems solve the original Project Euler problem and have a perfect score of 100% at Hackerrank, too.
yellow problems score less than 100% at Hackerrank (but still solve the original problem).
gray problems are already solved but I haven't published my solution yet.
blue problems are already solved and there wasn't a Hackerrank version of it (at the time I solved it) or I didn't care about it because it differed too much.

Please click on a problem's number to open my solution to that problem:

 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200
The 133 solved problems had an average difficulty of 16.9% at Project Euler and I scored 11,174 points (out of 12300) at Hackerrank's Project Euler+.
more about me can be found on my homepage.
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