Codeforces Round #274 (Div. 2)

A http://codeforces.com/contest/479/problem/A

枚举情况

 #include<cstdio>
 #include<algorithm>
 using namespace std;
 int main(){
     int a,b,c;
     while(~scanf("%d%d%d",&a,&b,&c)){
         int ans=;
         ans=max(ans,a+b+c);
         ans=max(ans,a*b*c);
         ans=max(ans,a*b+c);
         ans=max(ans,a+b*c);
         ans=max(ans,(a+b)*c);
         ans=max(ans,a*(b+c));
         printf("%d\n",ans);
     }
     return ;
 }

B http://codeforces.com/contest/479/problem/B

暴力，每次拿一个，然后排序。

 #include<cstdio>
 #include<algorithm>
 #include<vector>
 using namespace std;
 const int inf=0x3f3f3f3f;
 struct G{
     int val,id;
     friend bool operator <(const G &a,const G &b){
         return a.val<b.val;
     }
 }g[];
 struct A{
     int x,y;
 }now;
 vector<A> ans;
 int main(){
     int n,k;
     while(~scanf("%d%d",&n,&k)){
         int big=,sma=inf,cha;
         for(int i=;i<n;i++){
             scanf("%d",&g[i].val);
             g[i].id=i+;
             big=max(big,g[i].val);
             sma=min(sma,g[i].val);
         }
         cha=big-sma;
         ans.clear();
         while(k--&&cha){
             sort(g,g+n);
             g[].val++;
             g[n-].val--;
             big=;
             sma=inf;
             for(int i=;i<n;i++){
                 big=max(big,g[i].val);
                 sma=min(sma,g[i].val);
             }
             if(big-sma>cha) break;
             cha=big-sma;
             now.x=g[n-].id;
             now.y=g[].id;
             ans.push_back(now);
         }
         printf("%d %d\n",cha,ans.size());
         int len=ans.size();
         for(int i=;i<len;i++){
             printf("%d %d\n",ans[i].x,ans[i].y);
         }
     }
     return ;
 }

c

贪心

 #include<cstdio>
 #include<algorithm>
 using namespace std;
 const int M=;
 struct G{
     int a,b;
     friend bool operator <(const G &a,const G &b){
         return a.a<b.a;
     }
 }g[M];
 int main(){
     int n;
     while(~scanf("%d",&n)){
         for(int i=;i<n;i++){
             scanf("%d%d",&g[i].a,&g[i].b);
         }
         sort(g,g+n);
         int now=;
         for(int i=;i<n;){
             int s=i,t;
             int big=;
             int sma=0x3f3f3f3f;
             for(int j=i;j<n;j++){
                 if(g[i].a==g[j].a){
                     t=j;
                     big=max(big,g[j].b);
                     sma=min(sma,g[j].b);
                 }
                 else{
                     break;
                 }
             }
             if(big<g[i].a&&sma>=now){
                 now=big;
             }
             else{
                 now=g[i].a;
             }
             i=t+;
         }
         printf("%d\n",now);
     }
     return ;
 }

d

map 判断是否存在

 #include<cstdio>
 #include<map>
 using namespace std;
 const int M=1e5+;
 int a[M];
 int l;
 map<int,bool> mp;
 bool has(int x,int y) {
     if(mp[x+y]||mp[x-y]) return true;
     return false;
 }
 bool in(int x) {
     if(x>=&&x<=l) return true;
     return false;
 }
 int main() {
     int n,x,y;
     while(~scanf("%d%d%d%d",&n,&l,&x,&y)) {
         mp.clear();
         for(int i=; i<n; i++) {
             scanf("%d",&a[i]);
             mp[a[i]]=true;
         }
         bool fx=false,fy=false;
         for(int i=; i<n; i++) {
             if(has(a[i],x)) {
                 fx=true;
             }
             if(has(a[i],y)) {
                 fy=true;
             }
         }
         if(fx&&fy) {
             puts("");
             continue;
         }
         if(!fx&&fy) {
             puts("");
             printf("%d\n",x);
             continue;
         }
         if(fx&&!fy) {
             puts("");
             printf("%d\n",y);
             continue;
         }
         int ans=-;
         for(int i=; i<n; i++) {
             if(in(a[i]-x)&&has(a[i]-x,y)) {
                 ans=a[i]-x;
                 break;
             }
             if(in(a[i]+x)&&has(a[i]+x,y)) {
                 ans=a[i]+x;
                 break;
             }
             if(in(a[i]-y)&&has(a[i]-y,x)) {
                 ans=a[i]-y;
                 break;
             }
             if(in(a[i]+y)&&has(a[i]+y,x)) {
                 ans=a[i]+y;
                 break;
             }
         }
         if(ans!=-) {
             puts("");
             printf("%d\n",ans);
         } else {
             puts("");
             printf("%d %d\n",x,y);
         }
     }
     return ;
 }

end