99 lines
2.4 KiB
Text
99 lines
2.4 KiB
Text
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/* Simulates nodes which perform a map job */
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int[] map ((int) -> int f, int[] src, int len) {
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var tgt = new int[len];
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for (var i = 0; i < len; i = i + 1;) { tgt[i] = f(src[i]); }
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return tgt;
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}
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struct MapJob {
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(int) -> int f;
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int[] arr;
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int arrlen
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}
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int[] mapNode(MapJob j) { return map(j.f, j.arr, j.arrlen); }
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/* Simulates nodes which perform a reduce job */
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int reduce((int, int) -> int f, int[] arr, int len, int base) {
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var acc = base;
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for (var i = 0; i < len; i = i + 1;) { acc = f(acc, arr[i]); }
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return acc;
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}
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struct ReduceJob {
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int[] arr;
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int arrlen;
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(int, int) -> int f;
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int base
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}
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int reduceNode(ReduceJob j) { return reduce(j.f, j.arr, j.arrlen, j.base); }
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/* Generates an array of data, partitions it into map jobs and assigns
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them to virtual map nodes. When all data is mapped, reduces it into
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an answer and returns it */
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int square(int elt) { return elt * elt; }
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int sum(int acc, int elt) { return acc + elt; }
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int sumOfSquares(int[] arr, int arrlen, int numPartitions, int partitionLen) {
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/* Partition array into almost equal subarrays */
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var src = new int[][numPartitions];
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for (var i = 0; i < numPartitions; i = i + 1;) {
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src[i] = new int[partitionLen];
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}
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var j = 0;
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var k = 0;
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for (var i = 0; i < arrlen; i = i + 1;) {
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src[j][k] = arr[i];
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if (j == numPartitions - 1) {
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j = 0;
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k = k + 1;
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} else { j = j + 1; }
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}
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/* Build map-jobs */
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var mapJobs = new MapJob[numPartitions];
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for (var i = 0; i < numPartitions; i = i + 1;) {
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mapJobs[i] = new MapJob {
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f = square;
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arr = src[i];
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arrlen = partitionLen
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};
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}
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/* Map! */
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var tgt = new int[][numPartitions];
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for (var i = 0; i < numPartitions; i = i + 1;) {
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tgt[i] = mapNode(mapJobs[i]);
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}
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/* Build reduce-jobs */
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var reduceJobs = new ReduceJob[numPartitions];
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for (var i = 0; i < numPartitions; i = i + 1;) {
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reduceJobs[i] = new ReduceJob {
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f = sum;
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arr = tgt[i];
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arrlen = partitionLen;
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base = 0
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};
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}
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/* Reduce! */
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var acc = 0;
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for (var i = 0; i < numPartitions; i = i + 1;) {
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acc = acc + reduceNode(reduceJobs[i]);
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}
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return acc;
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}
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int program(int argc, string[] argv) {
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/* Initialize array with first n positive ints */
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var n = 30;
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var arr = new int[n];
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for (var i = 0; i < n; i = i + 1;) { arr[i] = i + 1; }
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/* Need partitionLen * numPartitions >= arr.length */
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var numPartitions = 5;
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var partitionLen = 6;
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return sumOfSquares(arr, n, numPartitions, partitionLen);
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}
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