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=0;
        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 0;
}

 

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[128];
struct A{
    int x,y;
}now;
vector<A> ans;
int main(){
    int n,k;
    while(~scanf("%d%d",&n,&k)){
        int big=0,sma=inf,cha;
        for(int i=0;i<n;i++){
            scanf("%d",&g[i].val);
            g[i].id=i+1;
            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[0].val++;
            g[n-1].val--;
            big=0;
            sma=inf;
            for(int i=0;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-1].id;
            now.y=g[0].id;
            ans.push_back(now);
        }
        printf("%d %d\n",cha,ans.size());
        int len=ans.size();
        for(int i=0;i<len;i++){
            printf("%d %d\n",ans[i].x,ans[i].y);
        }
    }
    return 0;
}

 

 c 

贪心

#include<cstdio>
#include<algorithm>
using namespace std;
const int M=5010;
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=0;i<n;i++){
            scanf("%d%d",&g[i].a,&g[i].b);
        }
        sort(g,g+n);
        int now=0;
        for(int i=0;i<n;){
            int s=i,t;
            int big=0;
            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+1;
        }
        printf("%d\n",now);
    }
    return 0;
}

 

 

d

map 判断是否存在

#include<cstdio>
#include<map>
using namespace std;
const int M=1e5+10;
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>=0&&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=0; i<n; i++) {
            scanf("%d",&a[i]);
            mp[a[i]]=true;
        }
        bool fx=false,fy=false;
        for(int i=0; i<n; i++) {
            if(has(a[i],x)) {
                fx=true;
            }
            if(has(a[i],y)) {
                fy=true;
            }
        }
        if(fx&&fy) {
            puts("0");
            continue;
        }
        if(!fx&&fy) {
            puts("1");
            printf("%d\n",x);
            continue;
        }
        if(fx&&!fy) {
            puts("1");
            printf("%d\n",y);
            continue;
        }
        int ans=-1;
        for(int i=0; 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!=-1) {
            puts("1");
            printf("%d\n",ans);
        } else {
            puts("2");
            printf("%d %d\n",x,y);
        }
    }
    return 0;
}

 

 

 

end