【879. 盈利计划】 动态规划

//空间可以降到2维

class Solution {
    private int MOD= 1000000007;
    public int profitableSchemes(int n, int minProfit, int[] g, int[] profit) {
        int len = profit.length;
        long[][][] dp = new long[n+1][minProfit + 1][len];
        for (int p = 0; p <= minProfit; p++) {
            for (int j = 0; j < len; j++) {
                dp[0][p][j] = 0;
            }
        }
        //初始化
        for (int n1 = 0; n1 <= n; n1++) {
            dp[n1][0][0] = 1;
            if (n1 >= g[0]) {
                dp[n1][0][0] = 2;
            }
            for (int i = 1; i < len; i++) {
                if (g[i] > n1) {
                    dp[n1][0][i] = dp[n1][0][i - 1];
                } else {
                    dp[n1][0][i] = dp[n1 - g[i]][0][i - 1] + dp[n1][0][i - 1];
                }
                dp[n1][0][i] %= MOD;
            }
        }
        //递推
        for (int n1 = 0; n1 <= n; n1++) {
            for (int p = 1; p <= minProfit; p++) {
                if( n1 >=g[0]){
                    if( p<=profit[0]){
                        dp[n1][p][0] = 1;
                    }else{
                        dp[n1][p][0] = 0;
                    }
                }else{
                    dp[n1][p][0] =0;
                }
                for (int i = 1; i < len; i++) {
                    if (n1 >= g[i]) {
                        if (p <= profit[i]) {
                            dp[n1][p][i] = dp[n1 - g[i]][0][i - 1] + dp[n1][p][i - 1];
                        } else {
                            dp[n1][p][i] = dp[n1 - g[i]][p - profit[i]][i - 1] + dp[n1][p][i - 1];
                        }
                    } else {
                        dp[n1][p][i] = dp[n1][p][i-1];
                    }
                    dp[n1][p][i] %= MOD;
                }
            }
        }
        return  (int)dp[n][minProfit][len-1];
    }
}