Description

Given n items with size nums[i] which an integer array and all positive numbers. An integer target denotes the size of a backpack. Find the number of possible fill the backpack.

Each item may only be used once.

Example

Given candidate items [1,2,3,3,7] and target 7, A solution set is: [7], [1, 3, 3]. return 2.

Solution

这题与Backpack IV唯一的区别就是不能重复放置，因此只要将第二个循环改成从大到小反向遍历即可。

public class Solution {
    /**
     * @param nums an integer array and all positive numbers, no duplicates
     * @param target an integer
     * @return an integer
     */
    public int backPackIV(int[] nums, int target) {
        int[] dp = new int[target+1];
        dp[0] = 1;
        for (int i = 0; i < nums.length; i++) {
            for (int j = target; j >= nums[i]; j--) {
                dp[j] += dp[j-nums[i]];
            }
        }
        return dp[target];
    }
}