c++のvectorの操作

vector_sample.cpp

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <cmath>
#include <numeric>

using namespace std;

int main() {
  vector<int> v = { 3, 5, 2, 4, 1 };
  printf("begin address: %d\n", v.begin());
  printf("max element address: %d\n", max_element(v.begin(), v.end()));
  printf("max element: %d\n", *max_element(v.begin(), v.end()));
  printf("max element idx: %d\n", max_element(v.begin(), v.end()) - v.begin());
  
  // 配列の和を計算．
  printf("sum all: %d\n", accumulate(v.begin(), v.end(), 0));
  // 配列の掛け算をしたものを計算．
  printf("multiple all: %d\n", accumulate(v.begin(), v.end(), 1, multiplies<int>()));
  
  // 部分和を求める．
  vector<int> w(5); // 先に要素数分のメモリを確保．
  partial_sum(v.begin(), v.end(), w.begin());
  for (int i = 0; i < w.size(); i++) {
    printf("to index %d: %d\n", i, w[i]);
  }
  return 0;
}

実行結果

begin address: 21163040
max element address: 21163044
max element: 5
max element idx: 1
sum all: 15
multiple all: 120
to index 0: 3
to index 1: 8
to index 2: 10
to index 3: 14
to index 4: 15