通过bitmap对100w数字进行排序去重

首先生成100w随机数，控制最大数

<?php
$i = 0;
do{
        $i++;
        $num = rand(0, 999999);
        echo $num."
";
}while($i < 1000000);

直接上代码

#include <stdio.h>
#include <string.h>

#define MAX 1000000

unsigned char set_bit(unsigned char x, int n){
        x = x | 1 << n;
        return x;
}

unsigned char clr_bit(unsigned char x, int n){
        x = x & ~(1 << n);
        return x;
}

int get_bit(unsigned char x, int n){
        int ret = (x >> n) & 1;
        return ret;
}

int main(){
        unsigned char x[MAX / 8 + 1];
        memset(x, 0, sizeof(x));
        FILE *fp = fopen("txt", "r");
        char buf[8];
        int i, idx, n;
        while(!feof(fp) && fgets(buf, sizeof(buf), fp)){
                sscanf(buf, "%d", &i);
                idx = i / 8;
                n = i % 8;
                x[idx] = set_bit(x[idx], n); 

        }
        fclose(fp);
        for(i = 0; i < MAX; i++){
                idx = i / 8;
                n = i % 8;
                if(get_bit(x[idx], n)){
                        printf("%d
", i);
                }
        }
}

运行效果