A：模拟辗转相除法时记录答案
B：3种情况：能减少2，能减少1，不能减少分别考虑清楚
C：利用一个set和一个multiset，，把行列分开考虑，利用set自带的排序和查询，每次把相应的块拿出来分成两块插入回去，然后行列分别取最大相乘的作为这次询问的答案
D：一个区间覆盖问题的变形，注意公式的话，很容易发现其实x，w对应的就是一个[x – w, x + w]的区间，然后求最多不重合区间即可
代码：
#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;ll a, b, ans;ll gcd(ll a, ll b) {if (!b) return a;ans += a / b;return gcd(b, a % b);}int main() {scanf("%lld%lld", &a, &b);gcd(a, b);printf("%lld\n", ans);return 0;}#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200005;int n;char a[N], b[N];int g[30][30];int vis[30];int main() {scanf("%d%s%s", &n, a + 1, b + 1);int sum = 0;for (int i = 1; i <= n; i++)if (a[i] != b[i]) sum++;for (int i = 1; i <= n; i++) {if (a[i] != b[i]) {if (g[b[i] – 'a'][a[i] – 'a']) {printf("%d\n%d %d\n", sum – 2, i, g[b[i] – 'a'][a[i] – 'a']);return 0;}g[a[i] – 'a'][b[i] – 'a'] = i;}}for (int i = 1; i <= n; i++) {if (a[i] != b[i]) {vis[b[i] – 'a'] = i;}}for (int i = 1; i <= n; i++) {if (a[i] != b[i] && vis[a[i] – 'a']) {printf("%d\n%d %d\n", sum – 1, i, vis[a[i] – 'a']);return 0;}}printf("%d\n-1 -1\n", sum);return 0;}#include <cstdio>#include <cstring>#include <algorithm>#include <set>using namespace std;int w, h, n;set<int> x[2];multiset<int> xx[2];char op[2];int v;set<int>::iterator it, l, r;multiset<int>::iterator tmp;long long gao(int tp) {x[tp].insert(v);it = x[tp].find(v);l = it; l–; r = it; r++;xx[tp].erase(xx[tp].find(*r – *l));xx[tp].insert(v – *l);xx[tp].insert(*r – v);long long ans = 1;tmp = xx[tp].end(); tmp–;ans *= *tmp;tmp = xx[!tp].end(); tmp–;ans *= *tmp;return ans;}int main() {scanf("%d%d%d", &w, &h, &n);x[0].insert(0); x[0].insert(w);x[1].insert(0); x[1].insert(h);xx[0].insert(w); xx[1].insert(h);while (n–) {scanf("%s%d", op, &v);printf("%lld\n", gao(op[0] == 'H'));}return 0;}#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200005;const int INF = 0x3f3f3f3f;struct Seg {int l, r;Seg() {}Seg(int l, int r) {this->l = l;this->r = r;}} seg[N];int n, x, w;bool cmp(Seg a, Seg b) {return a.r < b.r;}int main() {scanf("%d", &n);for (int i = 0; i < n; i++) {scanf("%d%d", &x, &w);seg[i] = Seg(x – w, x + w);}sort(seg, seg + n, cmp);int ans = 0;int r = -INF;for (int i = 0; i < n; i++) {if (seg[i].l >= r) {r = seg[i].r;ans++;}}printf("%d\n", ans);return 0;}
筑起梦想的鸟巢，开始人生的长跑，领先每回的冲刺，
