POJ1190

来源：互联网发布：减肥晚上吃什么知乎编辑：程序博客网时间：2024/05/22 06:09

刚开始做的时候把Hi>Hi+1忽略了，导致结果错误，而且剪枝不够彻底，要注意使用剩余的部分与当前结果相结合来剪枝。
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class BirthdayCake2 {

static int[][] minvs;static int n;static int m;static int mins = 10000000;public static void main(String[] args) throws FileNotFoundException {    // TODO Auto-generated method stub    minvs = new int[21][2];    minvs[1][0] = 1;    minvs[1][1] = 2;    for (int i = 2; i < 21; i++) {        minvs[i][0] = minvs[i - 1][0] + i * i * i;        minvs[i][1] = minvs[i - 1][1] + 2 * i * i;    }    @SuppressWarnings("resource")    Scanner sc = new Scanner(System.in);    sc = new Scanner(new File("files/birthdaycake"));    n = sc.nextInt();    m = sc.nextInt();    for (int i = 71; i >= m; i--) {        for (int j = 30; j >= m; j--) {            if (n - i * i * j >= 0)                dfs(i, j, n - i * i * j, m - 1, i * i + 2 * i * j);        }    }    if (mins == 10000000)        System.out.println(0);    else        System.out.println(mins);}private static void dfs(int prer, int preh, int nn, int mm, int cs) {    // TODO Auto-generated method stub    if (mm == 0) {        if (nn == 0 && cs < mins)            mins = cs;        return;    }    if (nn <= 0 || cs + minvs[mm][1] >= mins || 2 * nn / prer + cs >= mins            || nn < minvs[mm][0])        return;    if (mm == 1) {        if ((prer - 1) * (prer - 1) * (preh - 1) < nn)            return;        for (int r = prer - 1; r > 0; r--) {            if (nn % (r * r) == 0 && nn / (r * r) < preh)                if (cs + 2 * nn / r < mins) {                    mins = cs + 2 * nn / r;                    break;                }        }    } else {        for (int i = prer - 1; i >= mm; i--) {            for (int j = preh - 1; j >= mm; j--) {                dfs(i, j, nn - i * i * j, mm - 1, cs + 2 * i * j);            }        }    }}

}

sample input:
10000
8

sample output:
1532

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