hdu 2602 0 – 1背包

/*<br /> 好久沒有用java寫了。代碼寫的好醜的，簡單的0 - 1背包<br /> DP[i][j]表示前i個物品,背包容量為j的最優值</p><p>狀態轉移方程為<br />DP[i][j] = max(DP[i-1][j] , DP[i-1][j-v[i]] + w[i]);</p><p>時間複雜度N*V , 空間複雜度N*V</p><p>所以虛擬碼如下:<br />for i = 所有物品<br />for j = V to v[i]<br /> dp[j] = max(dp[j] , dp[j-v[i]] + w[i]);</p><p>空間最佳化到一維V</p><p> */<br />import java.io.*;<br />import java.util.*;</p><p>public class Main<br />{<br />public static void main(String[] args)<br />{<br /> Scanner cin = new Scanner(new BufferedInputStream(System.in));<br />int t;<br />t = cin.nextInt();<br />//while(t--)<br />for(int k = 1; k <= t; k++)<br />{<br />int n, v;<br />int a[];<br />a = new int [1000];<br />int b[];<br />b = new int [1000];<br />n = cin.nextInt();<br />v = cin.nextInt();<br />for(int i = 1; i <= n; i++)<br />{<br />a[i] = cin.nextInt();//價值<br />}<br />for(int i = 1; i <= n; i++)<br />{<br />b[i] = cin.nextInt();//體積<br />}<br />int sum[];<br />sum = new int [1000];<br />int dp[][];<br />dp = new int [1001][1001];<br />for(int i = 0; i < 1001; i++)<br />//for(int j = 0; j < 1001; j++)<br />dp[0][i] = 0;<br />//Arrays.fill(dp, (int)0);</p><p>for(int i = 0; i <= v; i++)<br />sum[i] = 0;</p><p>for(int i = 1; i <= n; i++)<br />for(int j = 0; j <= v; j++)<br />{<br />if(b[i] > j)<br />{<br />dp[i][j] = dp[i - 1][j];<br />continue;<br />}<br />if(dp[i - 1][j] > dp[i - 1][j - b[i]] + a[i])<br />dp[i][j] = dp[i - 1][j];<br />else<br />dp[i][j] = dp[i - 1][j - b[i]] + a[i];</p><p>}</p><p>for(int i = 1; i <= n; i++)<br />for(int j = v; j >= b[i]; j--)<br />{<br />if(sum[j] < sum[j - b[i]] + a[i] )<br />sum[j] = sum[j - b[i]] + a[i];<br />//System.out.println(sum[j]);</p><p>}</p><p>//System.out.println(sum[v]);<br />System.out.println(dp[n][v]);<br />}</p><p>}</p><p>}<br />