LeetCode/LeetCode/cpp/lc_0053.cpp at master · duycc/LeetCode · GitHub

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/**
 * @file     lc_0053.cpp
 * @brief    https://leetcode-cn.com/problems/maximum-subarray/
 * @author   YongDu
 * @date     2021-09-11
 */

//===------------------------- [Dynamic Program] --------------------------===//
//
//===----------------------------------------------------------------------===//
class Solution {
public:
  int maxSubArray(vector<int> &nums) {
    vector<int> result(nums.size());
    result[0] = nums[0];
    int maxSum = nums[0];
    for (int i = 1; i < nums.size(); ++i) {
      result[i] = std::max(nums[i], result[i - 1] + nums[i]);
      maxSum = std::max(result[i], maxSum);
    }
    return maxSum;
  }
};

//===------------------------- [Greedy Method] ----------------------------===//
//
//===----------------------------------------------------------------------===//
class Solution {
public:
  int maxSubArray(vector<int> &nums) {
    // 贪心
    int maxSum = INT_MIN;
    int curSum = 0;
    for (auto num : nums) {
      curSum += num;
      if (curSum > maxSum) {
        maxSum = curSum;
      }
      if (curSum < 0) { // 和为负数则直接舍弃
        curSum = 0;
      }
    }
    return maxSum;
  }
};