https://github.com/lzyrapx/notes
👍Some notes...
https://github.com/lzyrapx/notes
notes sb-admin
Last synced: 3 months ago
JSON representation
👍Some notes...
- Host: GitHub
- URL: https://github.com/lzyrapx/notes
- Owner: lzyrapx
- Created: 2018-07-17T13:08:35.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2019-10-21T12:43:15.000Z (over 6 years ago)
- Last Synced: 2025-06-15T10:51:40.022Z (12 months ago)
- Topics: notes, sb-admin
- Language: C++
- Homepage:
- Size: 17.9 MB
- Stars: 12
- Watchers: 2
- Forks: 7
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# 这是一些笔记.(This is my notes)
***
## Example:
## Notes
### 理性分析 C++(-O2) 和 JS 的性能差距.
### On Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz.
### Test1：
#### 最后一行：时间(ms)
```
#pragma GCC optimize("O2")
#include
using namespace std;
int main(int argc, char const *argv[]) {
int t = clock();
int a = 1000000000,b = 1;
while(a) {
b <<= 1;
a--;
}
printf("%d ms\n",clock() - t);
return 0;
}
// 0 ms
```
```
var t;
t = new Date;
var a = 1000000000,
b = 1;
while(a) {
b <<= 1;
a--;
}
console.log(new Date - t + "ms");
// 915ms
```
### Test2：
```
#pragma GCC optimize("O2")
#include
using namespace std;
int a[10000100];
void quick_sort(int a[], int l, int r) {
if (l < r) {
int i = l, j = r, x = a[l];
while (i < j) {
while(i < j && a[j] >= x) j--;
if(i < j) a[i++] = a[j];
while(i < j && a[i] < x) i++;
if(i < j) a[j--] = a[i];
}
a[i] = x;
quick_sort(a, l, i - 1);
quick_sort(a, i + 1, r);
}
}
int main(int argc, char const *argv[]) {
srand((int)time(0));
for(int i = 0;i < 10000000; i++) {
a[i] = rand();
}
int t = clock();
quick_sort(a,0,10000000);
printf("%d ms\n",clock() -t);
return 0;
}
// 1738 ms
```
```
function quick_sort(a,l,r) {
if (l < r) {
var i = l, j = r, x = a[l];
while (i < j) {
while(i < j && a[j] >= x) j--;
if(i < j) a[i++] = a[j];
while(i < j && a[i] < x) i++;
if(i < j) a[j--] = a[i];
}
a[i] = x;
quick_sort(a, l, i - 1);
quick_sort(a, i + 1, r);
}
}
var s,i,t;
for(i=0,s=[];i<10000000;i++) s.push(Math.random()*1E7|0);
t = new Date;
quick_sort(s,0,10000000);
console.log(new Date - t + " ms");
// 3080 ms
```
### Test3：
```
#pragma GCC optimize("O2")
#include
using namespace std;
const int maxn = 50000000;
int a[maxn];
int p[maxn],m[maxn];
int pc;
int main(int argc, char const *argv[]) {
int t = clock();
for(int i = 2; i < maxn; i++) {
if(m[i] == 0) {
p[++pc] = m[i] = i;
}
int k = 0;
for(int j = 1; j <= pc && p[j] <= m[i] && (k = p[j] * i) < maxn; j++) {
m[k] = p[j];
}
}
int ans = 0;
for(int i = 1; i <= pc; i++) {
ans ^= p[i];
}
printf("%d\n", ans);
printf("%d ms\n",clock() - t);
return 0;
}
// 338 ms
```
```
var pc = 0;
var m = [];
var p = [];
function solve() {
// console.log("ok");
var i;
for(i = 2 ;i < 50000000;i++) {
if(m[i] == null) {
// console.log(i);
p[++pc] = m[i] = i;
}
var k = 0;
var j ;
for(j = 1; j <= pc && p[j] <= m[i] && (k = p[j] * i) < 50000000; j++) {
m[k] = p[j];
}
}
// console.log("pc = " + pc);
var ans = 0;
for(var i = 1; i <= pc; i++) {
ans ^= p[i];
}
console.log("ans= " + ans);
}
t = new Date;
solve();
console.log(new Date - t + " ms");
// 8096 ms
```
### Test4：
```
#pragma GCC optimize("O2")
#include
using namespace std;
const int maxn = 1000;
int G[1000][1000];
int sed = 0;
inline int getRand()
{
return sed = (sed * sed * 73 + sed * 233 + 19260817) & 0x0000ffff;
}
int main(int argc, char const *argv[]) {
int t = clock();
for(int i = 0; i < maxn; i++) {
for(int j = 0; j < maxn; j++) {
G[i][j] = getRand();
}
}
for(int i = 0; i < maxn; i++) {
for(int j = 0; j < maxn; j++) {
for(int k = 0; k < maxn; k++) {
if(G[j][k] > G[j][i] + G[i][k]) {
G[j][k] = G[j][i] + G[i][k];
}
}
}
}
int ans = 0;
for(int i = 0; i < maxn; i++) {
for(int j = 0; j < maxn; j++) {
ans ^= G[i][j];
}
}
printf("%d\n", ans);
printf("%d ms\n",clock() - t);
return 0;
}
// 1718 ms
```
```
var sed = 0;
var G = new Array();
function getRand() {
var res = sed = (sed * sed * 73 + sed * 233 + 19260817) & 0x0000ffff;
// console.log("res = " + res);
return res;
}
function solve() {
// console.log("ok");
for(var i = 0; i < 1000; i++) {
G[i] = new Array();
for(var j = 0; j < 1000; j++) {
G[i][j] = getRand();
}
}
for(var i = 0; i < 1000; i++) {
for(var j = 0; j < 1000; j++) {
for(var k = 0; k < 1000; k++) {
if(G[j][k] > G[j][i] + G[i][k]) {
G[j][k] = G[j][i] + G[i][k];
}
}
}
}
var ans = 0;
for(var i = 0; i < 1000; i++) {
for(var j = 0; j < 1000; j++) {
ans ^= G[i][j];
}
}
console.log("ans= " + ans);
}
t = new Date;
solve();
console.log(new Date - t + " ms");
// 3440 ms
```
### Test5：
```
#pragma GCC optimize("O2")
#include
using namespace std;
const int maxn = 1000000000; // 1e9
typedef unsigned long long ull;
int P = 1000000007;
int main(int argc, char const *argv[]) {
int t = clock();
ull ans = 1;
for(int i = 1; i < maxn; i++) {
ans = ans * i % P;
}
printf("%llu\n",ans);
printf("%d ms\n",clock() - t);
return 0;
}
// 11953 ms
```
```
var P = 1000000007;
var maxn = 1000000000;// 1e9
function solve() {
// console.log("ok");
var ans = 1;
for(var i = 1; i < maxn; i++) {
ans = ans * i % P;
}
console.log("ans= " + ans);
}
t = new Date;
solve();
console.log(new Date - t + " ms");
// 32175 ms
```