View Compilation Error

0_0_25872965_21270.cpp: In function 'void change(int)':
0_0_25872965_21270.cpp:58:5: error: 'tree' was not declared in this scope
     tree[rt] = total;
     ^
0_0_25872965_21270.cpp: In function 'void build(int, int, int)':
0_0_25872965_21270.cpp:65:9: error: 'tree' was not declared in this scope
         tree[rt] = item;
         ^