sort函数比较cmp写法

hihocoder1566http://hihocoder.com/problemset/problem/1566

一直WA因为cmp的写法写错了，未能正确实现排序功能。

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<cstdlib>
 #include<string>
 #include<cmath>
 #include<vector>
 #include<stack>
 #include<iterator>
 #include<queue>
 #include<cctype>
 #include<map>
 #define lson l, m, rt<<1
 #define rson m+1, r, rt<<1|1
 #define IO ios::sync_with_stdio(false);cin.tie(0);
 #define INF 0x3f3f3f3f
 #define MAXN 100010
 const int MOD=1e9+;
 typedef long long ll;
 using namespace std;
 int t;
 typedef struct {
     char s1[], s2[];
     int sum;
 }Node;
 Node node[];
 map<char, int> mp;
 int cal(const char s[])
 {
     int len = strlen(s), ans=, last=mp[s[len-]];
     for(int i = len-; i >= ; i--){
         if(last-mp[s[i]] > ){
             last -= mp[s[i]];
         }
         else{
             ans += last;
             last = mp[s[i]];
         }
     }
     ans += last;
     return ans;
 }
 bool cmp(const Node a, const Node b)
 {
     if(strcmp(a.s1, b.s1) != ) return strcmp(a.s1, b.s1)<;
     else{
         return a.sum < b.sum;
     }
 }
 int main()
 {
     IO;
     mp['I']=;mp['V']=;mp['X']=;mp['L']=;mp['C']=;mp['D']=;mp['M']=;
     cin >> t;
     for(int i = ; i < t; i++){
         cin >> node[i].s1 >> node[i].s2;
         node[i].sum = cal(node[i].s2);
         //cout << cal(node[i].s2) << endl;
     }
     sort(node, node+t, cmp);
     for(int i = ; i < t; i++){
         cout << node[i].s1 << " " << node[i].s2 << endl;
     }
     return ;
 }