数字和的个数

    题目描述：给定一个正整数数组，要求求出给定数的和的个数是多少

   思路：此题运用动态规划进行求解，用dp[n][m]表示前ｎ个数中有和为ｍ的数的个数，则dp[n][m] = dp[n-1][m-a[n]]+dp[n-1][m];

public class Test1{public static void main(String[] args){int[] a = {5,5,2,2,1,8};int[][] dp = new int [7][16];for(int i = 0;i <= 15;i++)dp[0][i] = 0;for(int i = 1;i <= 6;i++ ){for(int j = 1;j <= 15;j++){if(j > a[i - 1])dp[i][j] = dp[i - 1][j - a[i - 1]] + dp[i - 1][j];else if(j == a[i - 1])dp[i][j] = 1 + dp[i - 1][j];else dp[i][j] = dp[i - 1][j];}}System.out.println(dp[6][15]);}}