作业2

P1776 宝物筛选

多重背包+二进制优化

#include<bits/stdc++.h>
using namespace std;
const int N = 1000005;
int v[N] , w[N] , num[N];
int n , m;
int f[N] ;
int cnt;
int main () {
    cin >> n >> m;
	for(int i = 1 ; i <= n ; i++){
        int a , b , c;
		scanf("%d%d%d" ,&a , &b , &c);
		for(int j = 1 ; j <= c;  j <<= 1){
			v[++cnt] = a * j;
			w[cnt] = b * j;
			c -= j;
		}
		if(c){
			v[++cnt] = a * c;
			w[cnt] = b * c;
		}  
	}
	  for(int i = 1; i <= cnt; i++){
	  	for(int j = m ; j >= w[i] ; j --){
	  		f[j] = max(f[j] , f[j - w[i]] + v[i]);
		 }
	  }
	  cout << f[m] << endl;	
 }

P1555 尴尬的数字

差一位即可

#include <bits/stdc++.h>
using namespace std;
char a1[100], b1[100];
int a[100] , b[100];
int main()
{
    cin >> a1 >> b1;
    int la = strlen(a1);
    int lb = strlen(b1);
    int ans1 = 0;
    for(int i = 0 ; i < la ; i ++){
    	a[i] = a1[i] - '0';
	}
	for(int i = 0 ; i < lb ; i ++){
		b[i] = b1[i] - '0';
	}
    for (int i = 0; i < lb; i++)
    {
        ans1 = ans1 * 3 + b[i] ;
    }
    int ans = 0;
    for (int i = 0; i < la; i++)
    {
        a[i] ^= 1;
        ans = 0;
        for (int j = 0; j < la; j++)
        {
            ans = ans * 2 + a[j] ;
        }
        int tmp = abs(ans - ans1);
        while (tmp % 3 == 0)
        {
            tmp /= 3;
        }
        if (tmp < 3)
        {
            cout << ans << endl;
            return 0;
        }
        a[i] ^= 1;
    }
    return 0;
}

P8845 [传智杯 #4 初赛] 小卡和质数

明显的结论题

#include<bits/stdc++.h>
using namespace std;
int a , b ;
int t;
int main () {
	cin >> t;
	while(t --){
	cin >> a >> b;
    if((a == 1 && b == 2) || (a == 2 && b == 1)){
    	cout << "Yes" << endl;
	} else{
		cout << "No" << endl;
	}
   }
   return 0;
}