代码随想录第53天|1143.最长公共子序列, 1035.不相交的线,53. 最大子序和

LeetCode.1143.最长公共子序列

题目链接:1143. 最长公共子序列 - 力扣(LeetCode)

思路:

class Solution {
public:
    int longestCommonSubsequence(string text1, string text2) {
        //dp[i][j]:长度为[0, i-1]的字符串text1与长度为[0, j-1]的字符串text2的最长公共子序列为dp[i][j]
        vector> dp(text1.size() + 1, vector (text2.size() + 1, 0));
        for(int i = 1; i <= text1.size(); i++) {
            for(int j = 1; j <= text2.size(); j++) {
                if(text1[i - 1] == text2[j - 1]) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                }
                else {
                    dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
                }
            }
        }
        return dp[text1.size()][text2.size()];
    }
};

LeetCode1035.不相交的线

题目链接:1035. 不相交的线 - 力扣(LeetCode)

思路:

class Solution {
public:
    int maxUncrossedLines(vector& nums1, vector& nums2) {
        vector> dp(nums1.size() + 1, vector (nums2.size() + 1, 0));
        for(int i = 1; i <= nums1.size(); i++) {
            for(int j = 1; j <= nums2.size(); j++) {
                if(nums1[i - 1] == nums2[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;
                else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
        return dp[nums1.size()][nums2.size()];
    }
};

LeetCode53. 最大子序和

题目链接:53. 最大子数组和 - 力扣(LeetCode)

思路:

class Solution {
public:
    int maxSubArray(vector& nums) {
        if(nums.size() == 0) return 0;
        //dp[i]:包括下标i(以nums[i]为结尾)的最大连续子序列和为dp[i]
        vector dp(nums.size());
        int result = nums[0];
        dp[0] = nums[0];
        for(int i = 1; i < nums.size(); i++) {
            dp[i] = max(dp[i - 1] + nums[i], nums[i]);
            if(dp[i] > result) result = dp[i];
        }
        return result;
    }
};

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