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How do you create a sparse array?

#include <stdio.h>
#include <stdlib.h>
#include <map>

class triple {
    int x;
    int y;
    int z;
    bool operator<(const triple &other) const {
        if (x < other.x) return true;
        if (other.x < x) return false;
        if (y < other.y) return true;
        if (other.y < y) return false;
        return z < other.z;

int main(int, char**)
    std::map<triple,int> data;
    triple point;
    int i;

    for (i = 0; i < 10000000; ++i) {
        point.x = rand();
        point.y = rand();
        point.z = rand();
        //printf("%d %d %d %d
", i, point.x, point.y, point.z);
        data[point] = i;
    return 0;
std::map data<string,int> data;
char ix[100];

sprintf(ix, "%d,%d", x, y); // 2 vars
data[ix] = i;

sprintf(ix, "%d,%d,%d", x, y, z); // 3 vars
data[ix] = i;

Tags: c++ oop hash maps data-structures

Source: By Ed. as answer to the question

This code snippet was collected from stackoverflow, and is licensed under CC BY-SA 3.0

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