My LeetCode Diary - Day43 Dynamic Programming

1049. Last Stone Weight II

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class Solution {
    public int lastStoneWeightII(int[] stones) {
        int sum = 0;
        for (int s : stones) {
            sum += s;
        }

        int target = sum / 2;
        int[][] dp = new int[stones.length][target + 1];
        for (int j = stones[0]; j <= target; j++) {
            dp[0][j] = stones[0];
        }

        for (int i = 1; i < stones.length; i++) {
            for (int j = 1; j <= target; j++) {
                if (j >= stones[i]) {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - stones[i]] + stones[i]);
                } else {
                    dp[i][j] = dp[i - 1][j];
                }
            }
        }

        System.out.println(dp[stones.length - 1][target]);
        return (sum - dp[stones.length - 1][target]) - dp[stones.length - 1][target];
    }
}

494. Target Sum

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class Solution {
    public int findTargetSumWays(int[] nums, int target) {
        int sum = 0;
        for (int i = 0; i < nums.length; i++) sum += nums[i];
        if ( target < 0 && sum < -target) return 0;
        if ((target + sum) % 2 != 0) return 0;
        int size = (target + sum) / 2;
        if(size < 0) size = -size;
        int[] dp = new int[size + 1];
        dp[0] = 1;
        for (int i = 0; i < nums.length; i++) {
            for (int j = size; j >= nums[i]; j--) {
                dp[j] += dp[j - nums[i]];
            }
        }
        return dp[size];
    }
}

474. Ones and Zeroes

Link

class Solution {
    public int findMaxForm(String[] strs, int m, int n) {
        int[][] dp = new int[m + 1][n + 1];
        int oneNum, zeroNum;
        for (String str : strs) {
            oneNum = 0;
            zeroNum = 0;
            for (char ch : str.toCharArray()) {
                if (ch == '0') {
                    zeroNum++;
                } else {
                    oneNum++;
                }
            }
            for (int i = m; i >= zeroNum; i--) {
                for (int j = n; j >= oneNum; j--) {
                    dp[i][j] = Math.max(dp[i][j], dp[i - zeroNum][j - oneNum] + 1);
                }
            }
        }
        return dp[m][n];
    }
}