A - White Cells
#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
typedef long long LL;
int main(){
int a,b,c,d;
cin >> a >> b >> c >> d;
cout << (a - c) * (b - d) << endl;
return 0;
}
B - Can you solve this?
#include <bits/stdc++.h>
using namespace std;
const int N = 20 + 5;
typedef long long LL;
int n, m, c;
int b[N], a[N][N];
int res = 0;
int main() {
cin >> n >> m >> c;
for (int i = 0; i < m; i++) cin >> b[i];
for (int i = 0; i < n; i++) {
int tmp = 0;
for (int j = 0; j < m; j++) {
cin >> a[i][j];
tmp += a[i][j] * b[j];
}
if (tmp + c > 0) res++;
}
cout << res << endl;
return 0;
}
C - Energy Drink Collector
#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
typedef long long LL;
struct node {
LL v, num;
} a[N];
bool cmp(node a, node b) { return a.v < b.v; }
int main() {
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i++) cin >> a[i].v >> a[i].num;
sort(a, a + n, cmp);
LL res = 0;
LL num = 0;
for (int i = 0; i < n; i++) {
if (num + a[i].num <= m) {
res += a[i].v * a[i].num;
num += a[i].num;
}
else{
res += a[i].v * (m - num);
break;
}
}
cout << res << endl;
return 0;
}
D - XOR World
给出a和b，求出a异或到b的和
一个偶数和比他大1的奇数异或得到1,根据此可以将计算优化到O(1)
#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
typedef long long LL;
LL a, b;
int main() {
cin >> a >> b;
if (a == b)
cout << b << endl;
else {
if (a % 2 == 0) {
if (b % 2 == 1) {
if (((b - a + 1)/2) % 2 == 0) cout << 0 << endl;
else cout << 1 << endl;
} else {
if (((b - a)/2) % 2 == 0) cout << b << endl;
else cout << (1ll^b) << endl;
}
}
else{
if(b%2==1){
if (((b - a)/2) % 2 == 0) cout << a << endl;
else cout << (1ll^a) << endl;
}
else{
if (((b - a - 1)/2) % 2 == 0) cout << (a^b) << endl;
else cout << (a^1ll^b) << endl;
}
}
}
return 0;
}