C++ 代码模板

记录一下常用模板。

 

快速幂运算

long long fastpow(int a, int b) {
    long long ret = 1;
    long long base = (long long)a;
    while (b != 0) {
        if (b & 1 != 0) {
            ret *= base;
        }
        base *= base;
        b >>= 1;
    }
    return ret;
}

 

并查集

#include <vector>
#include <iostream>
#include "unionset.h"


#define MAX_N 10000
int parent[MAX_N];
int rank[MAX_N];

void uninit(int n) {
    for (int i = 0; i < n; i++) {
        parent[i] = i;
        rank[i] = 0;
    }
}

int unfind(int x) {
    while (x != parent[x]) x = parent[x];
    return x;
}

void ununite(int x, int y) {
    x = unfind(x);
    y = unfind(y);
    if (x == y) return;
    if (rank[x] < rank[y]) {
        parent[x] = y;
    }
    else {
        parent[y] = x;
        if (rank[x] == rank[y]) rank[x]++;
    }
}

bool unissame(int x, int y) {
    return unfind(x) == unfind(y);
}

 

Trie结构

#include "header.h"

class TrieNode {
public:
    string word;
    TrieNode* child[26];
    TrieNode() {
        word = "";
        for (int i = 0; i < 26; i++) child[i] = nullptr;
    }
};

class Trie {
private:
    TrieNode * root;
public:
    Trie(vector<string> words) {
        root = new TrieNode();
        buildTrie(words);
    }
    void buildTrie(vector<string> words) {
        for (auto s : words) {
            TrieNode* tmpnode = root;
            for (auto c : s) {
                int idx = c - 'a';
                if (!tmpnode->child[idx]) tmpnode->child[idx] = new TrieNode();
                tmpnode = tmpnode->child[idx];
            }
            tmpnode->word = s;
        }
    }
    bool hasprefix(string prefix) {
        TrieNode* tmpnode = root;
        for (auto c : prefix) {
            if (!tmpnode->child[c - 'a']) return false;
            tmpnode = tmpnode->child[c - 'a'];
        }
        return true;
    }
    bool hasword(string word) {
        TrieNode* tmpnode = root;
        for (auto c : word) {
            if (!tmpnode->child[c - 'a']) return false;
            tmpnode = tmpnode->child[c - 'a'];
        }
        return tmpnode->word != "";
    }
};