codeforces669E【CDQ分治】

这篇博客详细介绍了如何解决Codeforces 669E问题,采用经典的CDQ分治策略。博主强调了在处理过程中需要考虑操作编号、时间及权值,并指出虽然可以使用树套树的方法,但CDQ分治依然直观易懂。文章提供了路人使用的树套树代码示例以及博主自己的CDQ分治实现。

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很模板的CDQ分治题。
需要考虑操作编号,操作时间,操作权值。
对于询问要找同时小于编号和时间的操作才影响当前的询问。然后搞一下就行了。。
甚至CDQ分治不用也行,树套树。。。
还是很好理解的,外层权值,内层时间。
cf上路人的有点NB的树套树代码

map<int, map<int, int>> tree;
 
void update(int x, int a, int delta) {
   
   
    for (int i = x; i <= (int)1e9 + 15; i += i & -i) {
   
   
        tree[a][i] += delta;
    }
}
 
int query(int x, int a) {
   
   
    int ans = 0;
    for (int i = x; i > 0; i -= i & -i) {
   
   
        ans += tree[a][i];
    }
    return ans;
}

----------------------------------------------------------------------

if (t == 1) {
   
   
   update(x, a
### Codeforces 887E Problem Solution and Discussion The problem **887E - The Great Game** on Codeforces involves a strategic game between two players who take turns to perform operations under specific rules. To tackle this challenge effectively, understanding both dynamic programming (DP) techniques and bitwise manipulation is crucial. #### Dynamic Programming Approach One effective method to approach this problem utilizes DP with memoization. By defining `dp[i][j]` as the optimal result when starting from state `(i,j)` where `i` represents current position and `j` indicates some status flag related to previous moves: ```cpp #include <bits/stdc++.h> using namespace std; const int MAXN = ...; // Define based on constraints int dp[MAXN][2]; // Function to calculate minimum steps using top-down DP int minSteps(int pos, bool prevMoveType) { if (pos >= N) return 0; if (dp[pos][prevMoveType] != -1) return dp[pos][prevMoveType]; int res = INT_MAX; // Try all possible next positions and update 'res' for (...) { /* Logic here */ } dp[pos][prevMoveType] = res; return res; } ``` This code snippet outlines how one might structure a solution involving recursive calls combined with caching results through an array named `dp`. #### Bitwise Operations Insight Another critical aspect lies within efficiently handling large integers via bitwise operators instead of arithmetic ones whenever applicable. This optimization can significantly reduce computation time especially given tight limits often found in competitive coding challenges like those hosted by platforms such as Codeforces[^1]. For detailed discussions about similar problems or more insights into solving strategies specifically tailored towards contest preparation, visiting forums dedicated to algorithmic contests would be beneficial. Websites associated directly with Codeforces offer rich resources including editorials written after each round which provide comprehensive explanations alongside alternative approaches taken by successful contestants during live events. --related questions-- 1. What are common pitfalls encountered while implementing dynamic programming solutions? 2. How does bit manipulation improve performance in algorithms dealing with integer values? 3. Can you recommend any online communities focused on discussing competitive programming tactics? 4. Are there particular patterns that frequently appear across different levels of difficulty within Codeforces contests?
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