【PAT 甲級】1002 A+B for Polynomials (25分)（map）

​​1002 A+B for Polynomials (25分)​​

題目

分析

#include <bits/stdc++.h>
using namespace std;
#define db(x) cout<<x<<endl

typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 1e4 + 10;
const ll mod = 2147483648;

int n, m;
map<int, double, greater<int> > mp;
double ans[N];
int a; double b;

int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d%lf", &a, &b);
    mp[a] += b;
  }
  scanf("%d", &m);
  for (int i = 0; i < m; i++) {
    scanf("%d%lf", &a, &b);
    mp[a] += b;
  }
  int cnt = 1;
  for (map<int, double>::iterator it = mp.begin(); it != mp.end(); it++) {
    if (it->second == 0) continue;
    ans[cnt++] = it->first;
    ans[cnt++] = it->second;
  }
  if (cnt == 1) {
    printf("0\n"); return 0;
  }
  printf("%d ", cnt >> 1);
  for (int i = 1; i < cnt; i += 2) {
    printf("%.0lf %.1lf%c", ans[i], ans[i + 1], " \n"[i==cnt-2]);
  }
  return 0;
}