如何用指针实现C++数组的滑动窗口 高效子数组处理技术

#include <iostream>
#include <vector>

using namespace std;

// 计算滑动窗口内的元素和
int calculateSum(int* start, int* end) {
    int sum = 0;
    while (start <= end) {
        sum += *start;
        start++;
    }
    return sum;
}

int main() {
    vector<int> arr = {1, 3, -1, -3, 5, 3, 6, 7};
    int windowSize = 3;
    int n = arr.size();

    if (n < windowSize) {
        cout << "窗口大小大于数组大小，无法滑动。" << endl;
        return 1;
    }

    int* windowStart = arr.data(); // 指向数组起始位置的指针
    int* windowEnd = windowStart + windowSize - 1; // 指向窗口结束位置的指针

    // 循环遍历数组，滑动窗口
    while (windowEnd < arr.data() + n) {
        // 计算当前窗口的和
        int currentSum = calculateSum(windowStart, windowEnd);
        cout << "窗口和: " << currentSum << endl;

        // 移动窗口
        windowStart++;
        windowEnd++;
    }

    return 0;
}

#include <iostream>
#include <vector>

using namespace std;

int main() {
    vector<int> arr = {1, 3, -1, -3, 5, 3, 6, 7};
    int windowSize = 3;
    int n = arr.size();

    if (n < windowSize) {
        cout << "窗口大小大于数组大小，无法滑动。" << endl;
        return 1;
    }

    int* windowStart = arr.data();
    int* windowEnd = windowStart + windowSize - 1;

    // 初始窗口的和
    int currentSum = 0;
    for (int i = 0; i < windowSize; ++i) {
        currentSum += arr[i];
    }
    cout << "初始窗口和: " << currentSum << endl;


    // 循环遍历数组，滑动窗口
    while (windowEnd < arr.data() + n -1) { //注意这里，循环条件要减1，避免越界
        // 移动窗口
        windowStart++;
        windowEnd++;

        // 更新窗口和：减去离开窗口的元素，加上进入窗口的元素
        currentSum = currentSum - * (windowStart-1) + *windowEnd;
        cout << "窗口和: " << currentSum << endl;
    }

    return 0;
}

#include <iostream>
#include <string>
#include <unordered_map>

using namespace std;

string minWindow(string s, string t) {
    unordered_map<char, int> need, window;
    for (char c : t) need[c]++;

    int left = 0, right = 0;
    int valid = 0; // 满足need条件的字符个数
    int start = 0, len = INT_MAX;

    while (right < s.size()) {
        // c 是将移入窗口的字符
        char c = s[right];
        right++;
        // 更新窗口数据
        if (need.count(c)) {
            window[c]++;
            if (window[c] == need[c])
                valid++;
        }

        // 判断左侧窗口是否要收缩
        while (valid == need.size()) {
            // 在这里更新最小覆盖子串
            if (right - left < len) {
                start = left;
                len = right - left;
            }

            // d 是将移出窗口的字符
            char d = s[left];
            left++;
            // 更新窗口数据
            if (need.count(d)) {
                if (window[d] == need[d])
                    valid--;
                window[d]--;
            }
        }
    }
    // 如果没有找到符合条件的子串，则返回空字符串
    return len == INT_MAX ? "" : s.substr(start, len);
}


int main() {
    string s = "ADOBECODEBANC";
    string t = "ABC";
    string result = minWindow(s, t);
    cout << "最小覆盖子串: " << result << endl; // 输出: BANC
    return 0;
}