92.背包问题(lintcode)

注意j-A[i-1]必须大于等于0，只大于0会报错

class Solution {
public:
    /**
     * @param m: An integer m denotes the size of a backpack
     * @param A: Given n items with size A[i]
     * @return: The maximum size
     */
    int backPack(int m, vector<int> A) {
        // write your code here
        int length = A.size();
        vector<vector<bool>> result(length+1,vector<bool>(m+1));
        for(int i = 0;i <= m;i++)
            result[0][i] = false;
        for(int j = 0;j <= length;j++)
            result[j][0] = true;
        for(int i = 1;i <= length;i++){
            for(int j = 1;j <= m;j++){
                if((j-A[i-1]) >= 0)
                    result[i][j] = result[i-1][j-A[i-1]] || result[i-1][j];
                else
                    result[i][j] = result[i-1][j];
            }
        }
        int max = 0;
        for(int i = 1;i <= length;i++){
            for(int j = 1;j <= m;j++){
                if(result[i][j] == true){
                    if(j > max)
                        max = j;
                }
            }
        }
        return max;
    }
};