|
|
package class45;
|
|
|
|
|
|
import java.util.HashMap;
|
|
|
import java.util.TreeSet;
|
|
|
|
|
|
public class Problem_2035_PartitionArrayIntoTwoArraysToMinimizeSumDifference {
|
|
|
|
|
|
public static int minimumDifference(int[] arr) {
|
|
|
int size = arr.length;
|
|
|
int half = size >> 1;
|
|
|
HashMap<Integer, TreeSet<Integer>> lmap = new HashMap<>();
|
|
|
process(arr, 0, half, 0, 0, lmap);
|
|
|
HashMap<Integer, TreeSet<Integer>> rmap = new HashMap<>();
|
|
|
process(arr, half, size, 0, 0, rmap);
|
|
|
int sum = 0;
|
|
|
for (int num : arr) {
|
|
|
sum += num;
|
|
|
}
|
|
|
int ans = Integer.MAX_VALUE;
|
|
|
for (int leftNum : lmap.keySet()) {
|
|
|
for (int leftSum : lmap.get(leftNum)) {
|
|
|
Integer rightSum = rmap.get(half - leftNum).floor((sum >> 1) - leftSum);
|
|
|
if (rightSum != null) {
|
|
|
int pickSum = leftSum + rightSum;
|
|
|
int restSum = sum - pickSum;
|
|
|
ans = Math.min(ans, restSum - pickSum);
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
return ans;
|
|
|
}
|
|
|
|
|
|
|
|
|
// arr -> 8 0 1 2 3 4 5 6 7
|
|
|
// process(arr, 0, 4) [0,4)
|
|
|
// process(arr, 4, 8) [4,8)
|
|
|
// arr[index....end-1]这个范围上，去做选择
|
|
|
// pick挑了几个数！
|
|
|
// sum挑的这些数，累加和是多少！
|
|
|
// map记录结果
|
|
|
// HashMap<Integer, TreeSet<Integer>> map
|
|
|
// key -> 挑了几个数，比如挑了3个数，但是形成累加和可能多个！
|
|
|
// value -> 有序表，都记下来！
|
|
|
// 整个过程，纯暴力！2^15 -> 3万多，纯暴力跑完，依然很快！
|
|
|
public static void process(int[] arr, int index, int end, int pick, int sum,
|
|
|
HashMap<Integer, TreeSet<Integer>> map) {
|
|
|
if (index == end) {
|
|
|
if (!map.containsKey(pick)) {
|
|
|
map.put(pick, new TreeSet<>());
|
|
|
}
|
|
|
map.get(pick).add(sum);
|
|
|
} else {
|
|
|
process(arr, index + 1, end, pick, sum, map);
|
|
|
process(arr, index + 1, end, pick + 1, sum + arr[index], map);
|
|
|
}
|
|
|
}
|
|
|
|
|
|
}
|
